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THE HUMAN BODY AND 
ITS ENEMIES 


BY 

' CARL HARTMAN, B. A., M. A. 

it 

Tutor in Zoology, University of Texas, 1903-4; County Superintendent of 
Public Instruction, Travis County, 1904-9; Professor of Biology, 

Sam Houston Normal Institute, 1909-12; Instructor in 
Zoology, University of Texas, 1912. 

AND 

LEWIS BRADLEY BIBB, B. S„ M. D. 

Registrar of Vital Statistics and Secretary State Board of Health, 1909-10; 
Secretary Texas Anti-Tuberculosis Association, 1908-; Resident 
Physician and Pathologist Texas School and Sani¬ 
tarium for Defectives, 1909-11; Member 
Austin Board of Health. 1908-. 


Illustrated by 

MARGARET BOROUGHS 
JOHN DOCTOROFF 
CARL HARTMAN 


PUBLISHED BY 

E. L. STECK 


AUSTIN, TEXAS 





Copyrighted, 1912, by 
Carl Hartman and Lewis Bradley Bibb, 



§ CI.A320540 
Too 1 


TABLE OF CONTENTS. 


CHAPTER PAGE 

I. Introduction . v ... 1 

II. Bacteria. 4 

III. Diseases That Are Catching. 10 

IV. Our Protection Against Disease Germs. ... 15 

V. Typhoid Fever. 29 

VI. Consumption or Tuberculosis. 42 

VII. Colds, Grip and Pneumonia. 52 

VIII. Meningitis and Diphtheria. 56 

IX. Malaria, Yellow Fever and Dengue. 61 

X. Quarantinable and Reportable Diseases. ... 67 

XI. Pellagra and Hookworm Disease. 75 

XII. Bubonic Plague. 80 

XIII. Disease Carriers... 83 

XIV. Insects Which Scatter or Carry Disease. ... 86 

XV. Keeping Germs Out op Our Drinking Water 100 

XVI. Disinfection or How to Kill Bacteria . Ill 

XVII. Vital Statistics. 119 

XVIII The Body a House of Many Parts. 125 

XIX. Why We Eat. 130 

XX. What We Eat. 134 

XXI. Pure Food. 140 

XXII. Getting the Food Ready for the Blood: 

Digestion . 151 

XXIII. Where Digestion Begins: The Mouth. 156 

XXIV. The Digestive Organs (continued). 162 

XXV. The Digestive Glands. 169 

XXVI. How the Food Is Taken Up By the Blood: 

Absorption . 174 

XXVII. The Making of Living Substance: Assimi¬ 
lation . 179 
























iv 

TABLE OF CONTENTS— Continued. 

CHAPTER ' PAGE 

XXVIII. Why We Breathe. 185 

XXIX. The Breathing Organs. 189 

XXX. Ventilation. 199 

XXXI. The Circulation of the Blood.. 205 

XXXII. The Blood and the Lymph. 216 

XXXIII. Excretion . 224 

XXXIV. The Regulation of Heat in the Body. 234 

XXXV. Locomotion: Bones and Joints. 243 

XXXVI. Locomotion: Muscles. 254 

XXXVII. The Nervous System: General. 263 

XXXVIII. The Brain. 267 

XXXIX. The Spinal Cord and the Sympathetic Sys¬ 
tem . 274 

XL. Care of the Nervous System. 284 

XLI. Alcohol, Narcotics and Stimulants. 291 

XXII. The Special Senses. 299 

XLIII. Hearing. 306 

XLIV. Sight .. 311 

XLV. Accidents and Emergencies. 326 

Appendix A.—Sanitary and Unsanitary Outhouses.... 334 
Appendix B.—The Sanitary Code for Texas. 337 





















PREFACE. 


An examination of school physiologies published within the 
last four or five decades discloses the changing viewpoints of 
teachers of this subject. First anatomy was stressed, then physi¬ 
ology became prominent, while in recent years leaders in educa¬ 
tional thought are agreed that hygiene is of paramount impor¬ 
tance. Within this recent period there has been a shifting of 
accent from dress and diet to the prevention of germ diseases. 
The most generally accepted course of today for elementary 
“ physiology ’ ’ is one that does not minimize any of the phases 
of the subject mentioned, but one that preserves a correct pro¬ 
portion among them. 

The essential principle of hygiene has ever been cleanliness. 
The race has developed an instinctive horror for the unclean. 
Since the discovery of micro-organisms as the causative agents 
of disease, however, our adherence to cleanliness has become 
specific and intelligent. There are, for example, many harm¬ 
less substances far more revolting than human blood containing 
malarial parasites. But modern hygiene teaches that the blood 
of a malarial patient, taken in conjunction with a certain species 
of mosquito, makes a combination which is, from a health stand¬ 
point, very “unclean/’ 

There is, therefore, a well-founded demand that children be 
taught the essentials of germ diseases and their prevention. The 
authors of the present volume have placed this material first, 
believing that its importance justifies this order of treatment. 

There is in some quarters a timidity in dealing with these 
topics of health and disease on the ground that increased knowl¬ 
edge along these lines would lead to a more pessimistic point 


vi 


of view. The important role of optimism in the preservation 
of health is well recognized. Yet, in view of our present knowl¬ 
edge of the wonderful defenses of the human body, it must be 
conceded that an understanding of them gives an increased 
confidence and renewed optimism based on fact and not merely 
on sentiment. 

A discussion of the anatomy of the human body has been 
reduced to a minimum; likewise, the physiology has been sub¬ 
ordinated to the principles of hygiene. Such a treatment is be¬ 
lieved to appeal to the reason of the child, for persuasion is 
more effective than arbitrary command. 

The fact has been borne in mind that “physiology and 
hygiene” is practically the only natural science that the great 
bulk of our people ever have an opportunity of studying. The 
scientific treatment has, therefore, been adhered to as closely 
as the intellectual advancement of the pupil for whom this work 
is intended would seem to allow. 

Aids to the memory, however, have not been omitted. A 
summary of the important points together with carefully se¬ 
lected questions at the end of each chapter will be found of 
help to the pupil in his study. Frequent review questions and 
cross references in the text afford ample opportunities for repe¬ 
tition. 

Experience in teaching science soon convinces one that poor 
thinking is largely due to vague mental concepts of things and 
relations. The laboratory method of “seeing for one’s self” has 
been stressed in these pages. The numerous experiments in¬ 
troduced throughout the book are all simple and can be per¬ 
formed easily and with very little outlay for apparatus and ma¬ 
terial. 

Illustrations are today considered a necessity in a modern 
scientific book, particularly in one intended for the young mind. 


This book contains more illustrations than any book of its kind 
that has come under our notice. With several exceptions, they 
were all drawn expressly for this book. For many of the illus¬ 
trations a distinct pedagogical value is claimed, particularly the 
types of illustrations exemplified by the section of the skin (Fig. 
176, shown in three dimensions) and by the figures of bone 
tissue (Figs. 189-191). 

The authors’ grateful acknowledgments of thanks and appre¬ 
ciation are due their many friends of the teaching and medical 
profession in Texas and other States for kind assistance and 
suggestions in the preparation of this work. 

Carl Hartman. 

Lewis Bradley Bibb. 

Austin, Texas, Aug. 1, 1912. 




CHAPTER T. 


Introduction . 


If it were your duty to care for and operate some fine piece 
of machinery, like an automobile, you would first want to 
know a great deal about the machine, its various parts, how 
they were put together, and how all parts worked in harmony 
to make the machine go. No doubt you know boys who would 
delight in taking an automobile to pieces and putting it to¬ 
gether again. We al¬ 
ways take pleasure in 
observing and tinder¬ 
standing a beautiful 
machine, such as a 
watch, an aeroplane, or 
an automobile. 

The Human Body is a Flg The driver ot an automobile 
Wonderful Machine.— Should study his machine. 

Now, it is the duty of each and every one of us to care for and 
operate a much finer machine than any of those mentioned, and 
that is the human body. Did you ever stop to think what a won¬ 
derful machine your body is? Think of the brain, with which 
we know and remember things, feel emotions, and control our 
acts. Consider the eye, which is a little camera with sensitive 
film and focussing apparatus. How wonderfully all the parts 
of the body are connected by the nerves, which act as tele¬ 
graph wires, carrying messages from the various parts to the 
brain, which is like the central office. Most wonderful of all, 




The Human Body and Its Enemies. 


consider how the food we eat becomes a part of ourselves. We 
must conclude then that the human body is the most marvel¬ 
lous machine in existence. If 
we are to operate this mar¬ 
vellous machine we certainly 
should understand something 
about it, in order that we 
may take proper care of it 
and see that it does its work 
properly. 

. We Must Learn What Dan- 



3 


Fig. 2. The aviator’s life depends 
on his mastery over his machine. 


gers Threaten Our Bodies. —The driver of 
an automobile, however, must know more 
than the parts of his machine; he must 
know also what kind of dangers are to be 
met in the road which he is to travel. He 
must know the whereabouts of cactus 
thorns, sharp stones, and deep sands, in 
order that he may avoid them. Just so, 
the driver of the human automobile must 
know what dangers beset him on his life- 

journey. The habit of drinking alcohol, for instance, is one 
danger that besets some of us. Impure foods are very 
harmful to the body, and they are one of the dangers that 
may befall any of us. One of the commonest dangers, how¬ 
ever, that lurks along our life-journey is disease or sickness 
due to germs. 



if] 

A Camera. 


Disease germs not only cause more than one-third of all 
deaths that occur in this State, but also cause most of the 
blindness and a large part of the illness which afflicts our 
citizens. And yet, we can not be harmed by disease germs 
unless the germs enter our system. In order, then, to protect 











Introduction. 


3 


ourselves against these little germ-enemies, we must study 
them, learn where they come from, and how they gain entrance 
into the human body. We shall then be in a position to avoid 


them, and thus steer our human automobile clear of this danger. 
If we understand our 


bodies, and also understand 
just what dangers threaten 
us and how to avoid them, we 
shall be more likely to suc¬ 
ceed in keeping ourselves in 
that pleasant con d i t i o n 
which we call health. 



Fig\ 4. The eye, a human camera. 


Important Points. 


1, The human body is more complex than any machine or 
instrument made by man. 


Fig:. 5. 


2 . We should understand 
this machine in order to 
keep its various parts in or¬ 
der. 

3. We should also know 
how best to avoid certain 
dangers which threaten us, 

A few of our germ enemies. suc h ag typhoid fever, tuber- 


' Jwi ^ ^ 


culosis or consumption and other diseases due to germs. 


Questions 

1. Why should we study the human body? 2. Name some things 
which can injure the body. 3. Name one important cause of blind¬ 
ness. 4. What percentage or proportion of all deaths in Texas is 
due to germs? 5. Name several things we should know about dis¬ 
ease germs in order to avoid them. 





CHAPTER II. 


Bacteria or Germs . 

I should hate to have to tell you in a single sentence 
what germs or bacteria are. Bacteria are such wonderful lit¬ 
tle beings, and are so different from the creatures that we know, 
that it is very hard to get an idea of what they really are. 
All of you have read in the fairy tales about certain fairies that 
were invisible. The story of bacteria is like a fairy tale, be¬ 
cause for many centuries we were surrounded by bacteria, and 
yet they were invisible to us, and in fact we never guessed 
or dreamed that they existed until long after Columbus dis¬ 
covered America. And bac¬ 
teria are invisible to this day, 
unless we use a microscope to 
aid the human eye, or unless 
we take a great many of the 
bacteria in a clump to look 
at. 

Size of Bacteria. —To be¬ 
gin with, then, bacteria are 
very small. If you took a colony of them and picked it out 
with a needle till you had little pieces that you could barely 
see with the naked eye, each one of these little pieces would 
contain hundreds and probably thousands of bacteria. Many 
of them are so small that it would take twenty-five thousand 
of them placed side by side to occupy the space of an inch. 
And as small as they are, each one has a definite shape. There 
are three varieties of bacteria from a standpoint of shape, the 
rods, the round ones and the spirals. You can see these 
in Fig. 6. 



Fig. 7. This shows how much smaller 
bacteria are than the finest cam¬ 
bric needle. 




Bacteria or Germs. 


Motion of Bacteria. —Some of them can swim about from 
one place to another, and others never move unless they are 
washed about or jostled in the fluid ’they live in. Those that 
move, either do so by squirm¬ 
ing along like a snake swim¬ 
ming, or else they have little 
tiny hairs growing all over 
their bodies and whip the wa¬ 
ter with these hairs. Of course 
the perfectly round ones can¬ 
not do any squirming, and 
unless they have little hairs 
on them they cannot move. 

Food of Bacteria. —The bacterium (for this is the word we 
use in speaking of a single one) has to have food, and many of 
them have to have oxygen just as we do. But he is so small 
that the food can soak in from the outside, and he does not 
need any mouth. Practically all of his active life is spent in a 
liquid, and the food simply dissolves in the liquid and passes 
through his very thin skin into his inside. For you know the 
entire bacterium isn’t nearly so thick as a sheet of tissue pa¬ 
per, and his skin must be really so thin that we cannot realize 
its true thinness. But some bacteria (here we use the plural 
word again) seem to secrete a juice of some kind that digests 
meat. The only difference between their digestion and ours 
however, is that they pour the juice over the meat or other 
food while it is still outside their bodies. They let the diges¬ 
tion occur outside their bodies, and then absorb or soak up the 
food in a liquid form. 

Toxins.—The bacterium is so small that he needs no kid¬ 
neys. Whatever of waste matter there is in his body can soak 
out, or ooze out, just as his food soaks in. And this is one way 



Fig-. 8.—The rod-shaped germs can¬ 
not move about rapidly like the 
ones with the little lashes on them. 


6 


The Human Body and Its Enemies. 


that some bacteria injure us. Some kinds of bacteria live in 
our bodies and pour out or ooze out their waste material in 
our bodies. If the waste material they pour out is poisonous 
to us, they make us sick. The poisonous 
material is called toxin, which means 
“poison.” Other bacteria form a waste 
material is called toxin, which means 
not make us sick unless they multiply fast 
enough to stop up some passage way in the 
body. 

Multiplication of Bacteria. —And bacteria 
can multiply very rapidly indeed. They 
seem to multiply by simply dividing in two. 
Each one splits half in two and you have 
two bacteria where only one bacterium w r as 
in the first place. Starting with one bac¬ 
terium, we may have many millions in a day or two. 


Fig. 9. This glass 
tube contains 
bacteria growing 
on gelatine. 


Ultra-Microscopic Bacteria. —In studying bacteria we must 
not lose sight of the fact that there are some bacteria too 
small to be seen even with a good microscope. No one has 
ever seen these germs. You may well ask how then do we 
know that they exist. We know only from their effects. For 
instance, we know that foot and mouth disease in cattle is 
caused by a germ, and the blood of an animal sick of this dis¬ 
ease, if injected into another animal, will cause that animal 
to catch the disease. Even if we filter the blood from the sick 
animal, so as to remove all particles large enough for us to 
see with the best microscope, it will still cause foot and mouth 
disease when injected into an animal. Our filters are fine 
enough to strain out all germs that are visible, and since the 
filtered blood still causes the disease, we must conclude that 
there are invisible germs in it. These germs are so small that 




Bacteria or Germs. 


i 

they pass easily through the filter and set up foot and mouth 
disease as soon as they reaeli their natural living place, which 
is the body of the cow. Possibly some intelligent pupil at 
present busy in one of our schools may some day invent a mi¬ 
croscope powerful enough to reveal these ultra-microscopic 
bacteria to our sight. 

At this time we tend to look on smallpox, yellow fever, 
measles and infantile paralysis as being due to small bacteria, 
which we call ultra-microscopic. Certain diseases which at¬ 
tack the lower animals have been proven beyond a doubt to 
be due to the ultra-microscopic germs. 

Where Bacteria Live. —We have said nothing yet about where 
the bacteria live. They live almost everywhere. They live in 
water, they live in milk, they live in the ground, they live in 
dust, they live in decaying fruits, and we might say they live 
everywhere, except where they have been removed in some 
way. The most important place they live is in certain 
parts of our bodies. There are some harmless bacteria always 
present in the mouth. There are a great many harmless bac¬ 
teria always present in the intestines. Some harmless varie¬ 
ties are in the skin, especially the outer horny layer, at all 
times. Certain kinds of bacteria cause milk to sour. Certain 
other kinds cause milk to curdle into cheese. Still other bac¬ 
teria live on the roots of clover and peas and enrich the soil. 

Harmless Germs and Disease Germs. —There are thousands 
of different kinds of bacteria, and probably not over a hun¬ 
dred different kinds that are harmful to man. There are some 
bacteria that do not multiply anywhere except in the human 
body, and which make poisons or toxins which make us sick 
or even kill us. These bacteria are dangerous. Typhoid fever, 
meningitis, tuberculosis, la grippe and diphtheria are all 
caused by bacteria. The bacteria are visible with the micro- 


8 


The Human Body and Its Enemies. 


scope, but are so small that they could not harm us except for 
the poisons which they make in our bodies. 

Disease Germs Multiply Only in the Body. —It is very 
important to remember that most of the bacteria which cause 
disease cannot live more than a few weeks or months outside 
the human body. And these harmful bacteria do not as a rule 
multiply at all except in the human body. This makes it much 
easier to avoid them and keep free of them, because all we 
have to do is to see that none of the bacteria from sick people 
get near us. Think how hard it would be to avoid typhoid 
fever, for instance, if the germs were found naturally in the 
ground. It is hard enough to avoid the germs when we know 
that they are found only where they have been thrown. 

How Bacteria Are Scattered. —The germs do seem to 
have great success in getting themselves scattered. Take, for 
example, the germs of diphtheria. They can be carried from 
one individual to another on such a little thing as a lead pen¬ 
cil, especially if the users of the pencil place its point in their 
mouths. Waving a soiled pocket handkerchief in the air may 
set the germs to floating in the air we breathe. The fingers 
which have touched such a handkerchief may grasp a door¬ 
knob and leave many germs behind. The next fingers that 
grasp the doorknob will take away some of the germs. The 
wash-woman, handling the linen, is especially likely to get 
the germs into her system. In a general way, every solid or 
liquid particle that leaves the body of anyone suffering from 
a germ disease may carry the germs of that disease. Whether 
it be saliva, tears, perspiration, bath water, or any other thing 
of this kind, it is dangerous, because it may have 
germs in it. 

Careless People. —Since we know now the exact germ that 
causes each one of the diseases mentioned, and since we know 


Bacteria or Germs. 


9 


just how the germs are carried from one man to another, it 
is only a question of time till we will get the diseases under 
control. This knowledge is so new that the majority of people 
either do not know these things, or cannot realize them. You 
will see men and women with sweet character who go about 
spreading disease germs and causing sickness and death. 
Have you not seen consumptives spit on the floor? It would 
be kinder if the consumptive would set a steel trap to catch 
little children by the foot instead of setting this disease trap for 
them. Boys and girls in school now learn a great deal more 
about disease germs than their parents did when they were 
in school. The spitting nuisance is dying out. People must 
expectorate, but they can expectorate into a cuspidor or spit¬ 
toon, or else carry several handkerchiefs, paper napkins or 
rags. 

Important Points. 

1. Bacteria are too small to be seen with the naked eye, 
and some of them are so small we have never even seen them 
with the best microscopes. 

2. Bacteria live almost everywhere; especially in decaying 
food and dirty places. 

3. Many bacteria live in our bodies, and a few are harm¬ 
ful to us. Most of the harmful ones make toxins which make us 
sick. 

4. Many people have never learned the importance of not 
spitting on the floor. 

Questions. 

1. How small are bacteria? 2. Can they all move about? 3. How 
do bacteria multiply? 4. Name some places where bacteria live. 5. 
are all bacteria harmful to man? 6. How do they injure us? 7. 
Name some of the ways that disease germs are carried from one 
person to another. 


CHAPTER III. 

Diseases That Are Catching. 

Did you ever have measles or mumps? If so, you could 
possibly' tell just whom you caught the disease from. In 
other words, you could trace the source of contagion or infec¬ 
tion. Some diseases, like measles and smallpox, are under¬ 
stood to be contagious, or catching. A better word to use is 
1 ‘ communicable. ” A communicable disease is one that can 
be comihunicated or given to another. 

Communicable Diseases. —There are a great many diseases 
that are communicable. Some diseases we now know to be 
communicable, but formerly we did not. For instance, typhoid 
fever is a communicable disease. We have always known that 
leprosy, cholera, smallpox, plague, measles, scarlet fever, hy¬ 
drophobia, diphtheria and others were communicable; but we 
have learned only in our own generation that consumption, 
typhoid fever, malarial chills and fever, yellow fever, menin¬ 
gitis,'granulated lids, infantile paralysis, erysipelas, and den¬ 
gue, are also communicable. A great many well informed and 
educated people today do not realize that these diseases are 
communicable. 

Scientists Who Gave Up Their Lives. —There have been many 
scientists who gave up their lives in an effort to find exactly 
how the dangerous communicable diseases are spread. In 1900, 
Dr. Lazear and Dr. Carroll, both United States Army surgeons, 
willingly contracted yellow fever in order to find the exact 
method by which it is spread; Dr. Lazear died after a few 
clays ; Dr. Carroll lived for several years, but finally died as a 
result of the yellow fever. Dr. Ricketts, a young physician of 


Diseases That Are Catching. 


11 



DANDRUFF 

S E.CRETION FROM E.YE- 
ECRETION FROM NOSE. 

>5PUTUn 

DEAp SKIM 
All ovex'body 

WASTE 

FROM KIDNEY 

AND 

ALIMENTARY CANA' 


.Mosquitoes. 

AIMS OTHER. !N6E.ct6 







Fi^. 9. This picture shows almost all the different ways by which germs 
or "contagion” can leave or enter the body. There is not one solid or 
liquid particle cast off from the human body which may not, under 
certain conditions, carry or convey disease. Beginning at the top, you 
will note that dandruff is cast off from the scalp. “Dandruff” is in 
all probability a contagious disease spread largely by combs and 
brushes in barber shops. Pus from the eye conveys sore eyes of sev¬ 
eral kinds, some of which can cause blindness. Secretion from the nose 
and mouth is the medium for spreading consumption, diphtheria, men¬ 
ingitis, paralysis of children, and other diseases. Dead skin from the 
surface of the body is believed to spread smallpox, scarlet fever, measles, 
and other diseases. Waste matter from the kidneys and bowels un¬ 
doubtedly conveys typhoid fever, dysentery, Asiatic cholera, hookworm 
disease, and others. The mosquito is the only insect pictured, but 
many other insects carry disease from one person to another. You 
will learn more about these in Chapter XIV. From this page, learn one 
lesson: all contagion is due to solid or liquid particles which leave 
the body of the sick, while absolutely all such particles are capable 
of carrying some disease. 
















12 


The Human Body and Its Enemies. 


Chicago, went to Mexico in 1909 to study jail fever. During 
his experiences he became sick with the disease and died. 

Diseases Are Conveyed by Solid or Liquid Particles That 
Leave the Body of the Sick. —By exposing themselves to dan¬ 
ger, these scientists have found out just how most of these 
communicable diseases are spread. And yet some people still 
speak as though we did not know how they are spread. It is 
very important for us to realize that these diseases are not 
all spread in the same way; but we do know how most of 
them are spread. They are always conveyed by solid or fluid 
particles which leave our bodies. The air cannot spread dis¬ 
ease except for the dust or little pieces of dried material that 
came from our bodies and float in the air. Water cannot 
spread disease except when the particles of solid or liquid 
material that leave our bodies are in the water. Even the 
mosquito cannot carry disease except when she has sucked 
up some of the blood of an individual that is sick. The fly 
is powerless to carry disease except when he has been walk¬ 
ing over some of the waste that is cast off from our bodies. 

How Disease Germs Leave the Body. —Try to rid your mind 
of that old, hazy, indefinite idea that “contagion” may be 
“atmospheric,” or due to filth, or to bad weather, or to an 
unhealthy climate. Instead, think of contagion as something 
definite, that you can see and weigh and feel. Let us take 
note of the different ways in which particles leave the body. 
We have first the waste materials, which are thrown off by 
the kidneys, the alimentary canal, and the skin. Then we 
have the dried skin, which peels off every part of the body; 
these little particles are believed to carry the germ of small¬ 
pox. Then we have the hair and nails, and the hair may 
spread a very troublesome disease called ring-worm of the 
scalp. Then there is the sputum and saliva from the mouth, 


Diseases That are Catching. 13 

and the nasal secretion, both of which are concerned in the 
spread of many different diseases, such as measles, scarlet 
fever, diphtheria, consumption, meningitis, leprosy, smallpox, 
and other diseases. The secretion from the eye is responsible 
for the spread of trachoma or granulated lids, and conjunc¬ 
tivitis, or sore eyes. All these things leave the body natu 
rally. In addition, certain insects take away from our bodies 
blood, which conveys malaria. There are then many different 
ways by which solid and liquid particles leave our bodies, 
and there is some disease germ which may be carried by al¬ 
most every one of these particles. To help us get a clear idea 
how communicable diseases are spread, let us take certain 
examples. 

The Typhoid Germ Is Thrown Off From the Body in Body 
Wastes. —Typhoid fever is spread especially by the body 
wastes, which are thrown out from the sick room on the 
ground. Flies light on it, dip their feet in it, and fly into the 
dining room and walk over our food. Or else, the rain washes 
these body wastes into the well, spring, or river, and we drink 
the water containing the typhoid germs. 

Tuberculosis Is Spread Especially by Dust From Dried Spu¬ 
tum. —For instance, a consumptive spits on the floor; the spit 
dries; and when the floor is swept, the dried spit is thrown 
up in the air in the form of dust, where it is inhaled by all 
those in the room. 

Malaria Spread by the Mosquito. —In malaria, yellow fever, 
and dengue, the disease is not spread by body waste; but the 
mosquito gets a drop of blood from a patient suffering from 
malaria, and then bites a well man; and the malaria or 
other germs are injected into the well man. 

Diphtheria Is Sometimes Spread by the Pocket Handker¬ 
chief. —The patient soils the handkerchief with secretion from 


14 


The Human Body and Its Enemies. 


his nose. In handling the handkerchief, his fingers get the 
secretion and germs on them. He then handles knife and 
fork, and door knobs, or shakes hands with others. The germs 
are thus passed on to the hands of others, who, in turn, pick 
at their noses or eat with their fingers, or possibly use a 
pocket handkerchief, and thus place the germs in the nose, 
where they can reach the throat and set up diphtheria. 

Granulated Lids or Sore Eyes Are Spread by the Secretion 
From the Eyes of One Suffering From the Disease. —The secre¬ 
tion or pus is collected on a handkerchief. At the same time 
some of it reaches the fingers. From the fingers it contami¬ 
nates lead pencils, towels, door knobs, etcr 

Every case of communicable disease is caused by some se¬ 
cretion or excretion from the body of some one sick with the 
disease. 

Important Points. 

1. All disease germs are carried from the body by some 
solid or liquid particles thrown off from the body. 

2. Sputum and body wastes are especially likely to contain 
disease germs. 

3. No disease can spread if we prevent the solid and liquid 

particles from leaving the patient and getting into or on some 
other person. * 

Questions. 

1. Name all the solid and liquid particles which leave the body. 
(For example, body wastes, perspiration, etc.) 

2. Name ten communicable diseases. 

3. Name three diseases spread by sputum. 

4. What is meant by communicable disease? 

5. Describe how disease germs from body wastes can get from 
the ground into a new patient. 


CHAPTER IV. 


Our Protection Against Disease Germs. 

From the chapters that have gone before, you have learned 
something of the enemies which attack our bodies from with¬ 
out, and it now remains for us to learn how wonderfully we 
are protected against these germ enemies. Let us not think 
for one instant that the germs have an easy 
fight even after they get into our bodies. 
Before any germ can make us sick, it must 
fight the battle of its life, and the human 
body wins out in the vast majority of cases. 
Did you know that the human body has a 
wonderful system of defense against disease 
germs ? 

The Skin as a Protective Covering. —To 

begin with, our skin is thick and horny on 
the outside and very few bacteria 
can penetrate it if it is kept healthy 
and whole. The best way to keep 
the skin healthy is to keep it clean 
with soap and water in reasonable 
amount. 

The Gastric Juice Kills Germs.— 

The stomach is well protected, too. 

It is the first stopping place of every¬ 
thing we swallow. The stomach is 
bathed at all times in a good anti¬ 
septic fluid, the gastric juice. The gastric juice is fatal to 
germs. It contains hydrochloric acid, and the acid itself will 
kill most germs. The pepsin will also digest germs, and so if our 
digestion is good not many germs will pass through the stomach. 



Fig. 12. The gastric juice in 
the stomach is fatal to 
most germs. 



Fig. 11. The skin 
showing its pro¬ 
tective horny 
layer. 



16 


The Human Body and Its Enemies. 


Another Protection Against Germs. —But the body has an¬ 
other way of protecting itself against germs after they once 
get a foothold, and this is the most wonderful and beautiful 
safeguard that it is possible to imagine. This protection is 
shown in the case of measles. Did you ever notice that we 
have measles only once 1 ? And when we have it, it gets worse 
for about four or five days and then commences to get better. 
Now, why is this? 

It is because the one attack has taught our body how to pro¬ 
tect itself against the germ of measles. Just how the body 
does this we do not entirely know; but it is certainly plain that 
the body has hit upon some plan to protect itself against 
measles. This is very wonderful, and yet it is of so common 
occurrence that we pass it by without thinking much about it. 

The Blood of a Typhoid Patient Will Kill the Typhoid Germ. 
—Now, typhoid fever is another disease that usually can af¬ 
fect the body only once. After one attack of typhoid fever, 
as in measles, the body learns to protect itself. It has also 
been noticed that the blood of a patient just recovering from 
typhoid fever has the power of killing the typhoid germ. This 
experiment is often tried in order to see if the patient has 
really had typhoid fever. A few known typhoid germs from 
some other source are taken on a glass slide and placed under 
a microscope; these germs can be seen moving about at a great 
rate, changing from place to place each second. Then if a very 
small drop of the blood of a typhoid patient is mixed with the 
germs, they stop moving, collect together in clumps, and may 
die. Blood from one who has never had typhoid fever will not 
harm the typhoid germs. This shows that during the course of 
typhoid fever, the human body has formed protective sub¬ 
stances which have the power to kill the germs of the disease; 
and these protective substances are found in the blood. 


Otr Protection Against Disease Germs. 


17 


Immunity. —In this experiment, the typhoid germs are killed 
and are clumped together so they cannot move. In other germ 
diseases other protective substances are formed in the blood 
which may cause the germs to dissolve in the blood. This is, of 
course, fatal to the germs. Whenever the human body has in 
any way acquired the power to resist a disease, so that the 
disease cannot affect it, we say that the body is immune to the 
disease. One who has had measles, is immune to measles; after 
one lias had an attack of typhoid, he is immune to typhoid. 

We Can Produce an Immunity. —We know why the body be¬ 
comes immune in certain cases, because we can prove that there 
are protective substances in the blood. If we could only 
cause these protective substances to be formed in the blood, we 
could make the body immune and prevent the disease. You 
can see how desirable it would be to make people immune to 
any dangerous epidemic disease, that is, to immunize them. 
We do have at the present time some method of producing 
immunity in several diseases. When we produce an immunity 
in order to prevent disease we call it an “artificial immunity.” 
The first disease for which an artificial immunity was pro¬ 
duced, without the occurrence of the disease, was smallpox. 

Jenner Produced the First Artificial Immunity. —A young 
English physician, by the name of Jenner, stumbled by acci¬ 
dent on this method of producing an artificial immunity to¬ 
ward smallpox in the latter part of the nineteenth century. 
He did not know at that time that disease germs existed. He 
did not know any protective substances were produced by the 
body. But he did notice that every man who caught cowpox 
was afterward immune to smallpox. He observed this for some 
time, and it finally occurred to him to give cowpox to people 
in order to make them immune to smallpox. He tried it, and 
found that any one who caught cowpox could not be harmed 


18 


The Human Body and Its Enemies. 


by smallpox. Since cowpox is a harmless disease, this method 
of producing an immunity against the dreaded smallpox soon 
became very popular, and has been so until this day. 
Now, the young physician did not know how the im¬ 
munity was produced, but we now know that what 
he did was to place weakened smallpox germs into the 
patient. Cowpox is due to the same germ as smallpox, 
but when it affects the cow it becomes so weakened that it is 
almost harmless toward humans. These weakened smallpox 
germs then were put into the skin of the patient’s arm, and 
his blood soon became filled with protective substances against 
the smallpox germs. After this, the individual was immune 
to smallpox. You see, the germs were too weak to do any 
harm to the body, but were capable of causing the body to 
form the protective substances. 

All Artificial Immmunity Is the Result of Injecting 
Weakened or Dead Germs or Their Toxins Into the Body.— 

Owing to the work of Louis Pasteur, a Frenchman, who did 
his work about fifty years ago, we now know that disease 
germs can be weakened in various ways so that they can be 
put into the body without injuring the body, and yet produce 
an immunity. One way to weaken the germs is to chill them. 
Another way is to heat them. In fact, if the germs be killed 
completely, so that they cannot multiply at all in the body, 
they may in some cases cause the body to become immune. 
So we have learned two important things: first, when the body 
is affected by any disease, the body may produce protective 
substances which are found in the blood, and which may pro¬ 
tect the body completely against the disease germs of that 
particular disease. And, second, it is possible in some cases 
to place weakened or dead germs in the body, so that the body 


Our Protection Against Disease Germs. 


19 


makes the protective substances and becomes immune without 
having had the disease. 

Scientists Are Trying to Produce Artificial Immunity 
Against Other Diseases. —At this time hundreds of men are 
busy trying to find a way to make us immune to the dangerous 
diseases, especially tuberculosis, or consumption. No way is 
known yet to immunize one against this disease. We do have, 
however, methods of immunizing against the following dis¬ 
eases: smallpox, rabies or hydrophobia, typhoid fever and 
Asiatic cholera. 

Vaccines. —These immunizing remedies, consisting of dead 
or weakened disease germs, are called vaccines. Formerly 
smallpox vaccine was the only vaccine known, but w r e now 
have typhoid vaccine, cholera vaccine and others. 

The Immense Value of Typhoid Vaccination. —A striking ex¬ 
ample of the value of vaccination against typhoid fever was 
seen in the maneuvers of the United States army at San An¬ 
tonio in the summer of 1911. Many thousands of soldiers were 
camped in San Antonio for several months during the typhoid 
season. Most of the soldiers had been immunized against ty¬ 
phoid fever by the injection of dead typhoid bacilli. Not one 
single soldier that had had the full dose of the dead bacilli 
developed typhoid fever. In the Spanish-American War 
there were twenty thousand cases of typhoid fever and two 
thousand deaths. This was before the army surgeons had 
commenced the use of the dead typhoid germs. As a rule, 
when a large army takes the field more men are killed by 
typhoid fever than by bullets. You can understand how the 
germs of typhoid are always present in all large crowds of 
men, because there are so many typhoid carriers in the world. 
In this country it would probably be almost impossible to get 
together two thousand men without having a few typhoid 


20 


The Human Body and Its Enemies. 

carriers among the number. You will learn in a later chap¬ 
ter lhat a typhoid carrier is one who has typhoid germs in his 
body, but who is not sick. When you take into account the fact 
that all large armies have always suffered from typhoid fever, 

you will see that the good health of the soldiers at San Antonio 
was something new in the history of the world. 

At the time meningitis was prevalent in Texas, in 1911 and 
1912, some physicians used injections of the dead meningitis 

germs in order to immun¬ 
ize certain persons against 
the disease. It is to be 
hoped that as time goes 
on, other vaccines will be 
perfected, so that epidem¬ 
ics will be a rare occur¬ 
rence. 

Antitoxins an d Ser¬ 
ums. —Up to this time we 
have noticed how we may 
produce an artificial im¬ 
munity by injecting dead 
or weakened bacilli into 
the body. There is another way we may produce a partial ar¬ 
tificial immunity, which does not last very long, and this we 
will now take up. We can first immunize an animal by in¬ 
jecting the weakened or dead bacilli, and then use the serum 
of the animal to immunize human beings. Blood serum is the 
clear yellowish liquid that forms when blood clots or coagu¬ 
lates. The best example of this is the serum we use to prevent 
or cure diphtheria. In order to obtain this serum, we first 
immunize the horse against the poison or toxin formed by the 
diphtheria bacillus. We do this by injecting the horse with 



Fig:. 13. Injecting the horse with diph¬ 
theria toxin in order to form diph¬ 
theria antitoxin in his blood. 
















Our Protection Against Disease Germs. 


21 


gradually increasing amounts of the diphtheria toxin. When 
we have done this, no matter how much toxin we inject, the 
horse is uninjured, for his blood contains protective substances 
which prevent the diphtheria toxin from harming him. If 
now we bleed the horse and take his serum it contains the 
protective substances, and this serum, injected into a child 
with diphtheria, will cure the child. What we have done is 
to immunize the horse, and then borrowed the immunizing 
substances from the horse. Of course, the serum from the 
horse must be handled in a very cleanly manner. The picture 
shows a horse being injected with the diphtheria toxin. The 
serum used to immunize human beings, in this case, horse 
serum, is called “anti-toxin.” “Toxin” means “poison,” 
and “antitoxin” means “against the poison,” because the se¬ 
rum counteracts the poison of the germ. 

Tetanus or Lockjaw, Meningitis and Diphtheria, Are Treated 
by Serum or Anti-Toxin. —An attempt has been made to pro¬ 
duce serums for the cure of many of the communicable dis¬ 
eases, including even tuberculosis; but up to this time diph¬ 
theria, meningitis and tetanus or lockjaw, are the only dis¬ 
eases that have been cured by serum. You will, of course, 
notice the difference between immunizing and curing. To im¬ 
munize a person you inject the serum or vaccine and prevent 
the disease from developing; but to cure the patient, you in¬ 
ject the serum after the patient is sick of the disease. We 
believe that the serums used for the cure of diphtheria, teta¬ 
nus and meningitis are all valuable for immunizing persons, 
but the immunity does not last so long as when we produce 
an immunity by injecting the dead or weakened bacilli. It is 
very important to notice that the tetanus serum is of very 
little value after the patient has developed tetanus. If we 
inject the serum, however, immediately after the nail thrust 


22 


The Human Body and Its Enemies. 


has been received, the serum will almost always prevent the 
development of tetanus or lockjaw. For this reason it is 
important that all wounds made by explosions or nails should 
be treated properly at once. You will learn more of this in 
chapter XLY. 

Smallpox Vaccination Is of Greater Importance Than Any 
Other Immunizing Remedy. —Of the vaccines and serums men¬ 
tioned, smallpox vaccine is by far the most important, be¬ 
cause smallpox is the most contagious of all diseases. Before 
the discovery of vaccination, smallpox attacked the majority of 
all citizens. You might well ask, why is smallpox so conta¬ 
gious? Smallpox is very contagious, and in epidemic form 
is very hard to control, for the following reasons: first, al¬ 
most everybody is susceptible to smallpox, and takes it the 
first time exposed to it; second, the smallpox germ is given 
off from the body in enormous numbers, both in the sputum 
and nasal discharges, and in the particles of dead skin which 
you have read about in the chapter on “Diseases That Are 
Catching; M third, the smallpox germ is very long-lived, and 
will live in clothing for months; fourth, the skin does not 
show any eruption for several days after a smallpox patient is 
taken sick, but during this time the patient is giving off the 
germs by millions, and consequently is spreading the disease 
to dozens of people before he knows he has it. All these 
things make it almost impossible to control smallpox except 
by vaccination. 

Smallpox Is a Very Fatal Disease.— It is absolutely neces¬ 
sary to control smallpox in any way possible for it is a very 
fatal disease. In some epidemics as many as forty to sixty 
per cent of all cases die. Among those that do not lose 
their lives, many are disfigured for life by the pits or scars. 
Others are weakened in various ways so that they are never 


Our Protection Against Disease Germs. 


23 


able to bear the burdens of life as they should. And so we see 
many reasons why we must limit the occurrence of smallpox. 



Fig-. 14.—Two children in the municipal hospital of Philadelphia, one unvac¬ 
cinated and the other vaccinated on the day of admission. The crust 
is still seen upon the leg. This child remained in the hospital with its 
mother for three weeks, and was discharged perfectly well. The un¬ 
vaccinated child who was admitted with smallpox died. 

Vaccination Is Practically a Sure Preventive of Smallpox, 

and there is no single fact in science which has been proven 
more thoroughly than this. For the first few years after vac- 






24 


The Human Body and Its Enemies. 


cination the protection is practically complete, and after that 
it is gradually lost. The value of the protection afforded by 
vaccination is shown by a Texas epidemic which occurred 
since 1910. In this epidemic, there were ninety-eight who had 
the disease. Out of this number only two had ever been vac¬ 
cinated at all; one of these was an old man, who was vacci¬ 
nated sixty years ago when he was a child; the other had been 
vaccinated over fifteen years. Neither of these men had the 
disease in its worst form, and both recovered. Many of the 
unvaccinated died. In May, 1904, the United States Army Ship 
Liseum left Manila with 292 persons on board. During the 
first week at sea an unvaccinated child became ill with small¬ 
pox. Everyone on board except three persons had been vac¬ 
cinated. Inside of fourteen days all three of these persons 
developed smallpox, while not a single person of the 289 vac¬ 
cinated ones took the disease. The medical officers of the 
United States Government strongly recommend vaccination, 
because they know it is the only practical way to keep down 
smallpox. 

It Is Our Duty to Be Vaccinated. —In thinking over the 
question of vaccination we should remember that we not only 
owe it to ourselves to be vaccinated, in order to protect our¬ 
selves, but we also owe it to our fellow citizens to be vacci¬ 
nated in order to protect them. Nowhere else can we affect 
our neighbors more than by our health; if we take a conta¬ 
gious disease we are very likely to cause someone else to 
take it. 

When and How Often to Vaccinate. —Every child should be 
vaccinated before starting to school. If this vaccination does 
not take, it gives no protection and should be repeated until 
it does take. After one good scar has been formed there will 
be complete immunity for several years and partial immunity 


Our Protection Against Disease Germs. 


25 


all through life. It is well tQ vaccinate again about ten years 
after the first vaccination, and if this takes, the immunity is 
generally complete for life. 

Vaccination Will Protect Even If Done After Exposure to 
Smallpox. —The picture shows two babies who were kept in 
the same hospital. The story of these children is given under 
the picture. One important lesson to learn from this picture 
is this: vaccination will prevent smallpox, even after exposure 
has taken place. In other words, if you are exposed to small¬ 
pox today and are vaccinated immediately, the vaccination will 
develop in time to prevent the smallpox. This is due to the 
fact that vaccination develops more rapidly than smallpox. 
We believe that smallpox enters the body through the 
nose, and it takes it several days to develop. When we vac¬ 
cinate, we give the vaccine a certain advantage, and it de¬ 
velops more rapidly, thus “heading off”.the smallpox. 

The White Cells of the Blood Destroy Bacteria and Germs.— 
In studying vaccination against smallpox, however, let us not 
forget that this is only one 
kind of artificial immunity. 

We have studied also the ar¬ 
tificial immunity due to se¬ 
rum from an immunized ani¬ 
mal, for instance, the horse 
serum, which contains diph¬ 
theria antitoxin. Then we 

have studied the protection which our skin affords us, and 
the protection afforded by the gastric juice which kills germs 
in the stomach. 

There is one other protection that is very important and 
that is due to the white blood cells. These little cells act like 
little soldiers or policemen, and swallow up all the bacteria 



Fig. 15.—White cell of the blood 
swallowing- and digesting- germs. 



26 


The Human Body and Its Enemies. 


they can get in reach of. They collect in all sore places or 
inflamed places. They swallow the bacterium if they can, 
but if the bacterium is too poisonous they get close to him 
anyway and die there. There is no more heroic example in 
the world than that of these little cells trying to protect us. 
They try either to swallow the germ, or to block the way so 
the germ cannot spread through our body. If it is necessary 
they will block the way with their dead bodies. This is one 
example of unselfishness that cannot be surpassed in the world. 
The little white cells rush to any place of danger, and take up 
their stand to prevent the bacteria from spreading. They 
get so close to the danger that they die, but they seem never 
to retreat. The dead bodies of these little white cells make 
up the fluid which we call corruption or pus, such as that 
which comes out of a boil or rising when it is opened. We 
have been protected, but the little white cells have lost their 
lives for us. 

From what we have learned, you see that we have many 
ways of protecting ourselves against bacteria. When they 
try to live in our bodies, they usually fail and lose their lives. 
As soon as the bacteria start to multiplying anywhere in our 
bodies, our bodies start to making the antitoxins, and as a rule 
the bacteria are killed in a short time. 

Our Body Is Well Protected Against Bacteria. —There are 
probably other ways by which the body protects itself which 
we know T nothing about. For years we did not know about 
these, and it is almost sure that as we learn more about our¬ 
selves, we shall learn still more wonderful things. 

No Need for Alarm. —If you take good care of yourself and 
try to live well you need not feel apprehensive or frightened 
about disease germs. Live by the rules in this book until you 
find better rules to live by, but remember that your body is a 


Our Protection Against Disease Germs. 


27 


marvelous creation, a wonderful thing, and that it has not 
been made and put here without protection. 

Important Points. 

1. The human body has a very complicated and very won¬ 
derful set of defenses against disease germs. 

2. The power of the body to resist disease germs is called 
immunity. 

3. Nearly all the dangerous germ diseases except diphthe¬ 
ria and pneumonia are followed by an immunity; that is, after 
one attack, we are immune against the particular disease. 

4. The first physician to immunize a patient artificially was 
•Jenner. over a hundred years ago, and he produced an im¬ 
munity against smallpox by giving a patient cowpox, a harm¬ 
less disease. 

5. Today we have two ways of producing an artificial im¬ 
munity; first, by injecting weakened or dead bacilli, as in the 
case of smallpox or typhoid fever; and, secondly, by injecting 
the serum of an animal that has been immunized, as in diph¬ 
theria, tetanus and meningitis. 

6. The white cells of our blood attack some disease germs, 
and either swallow them or are killed by them. 

7. Smallpox is so contagious that we cannot control it with¬ 
out vaccination. 

8. Vaccination is a safe and easy method of controlling 
smallpox. 

Questions. 

1. How does the skin protect us against disease germs? 2. How 
does the stomach or gastric juice kill bacteria? 3. Name one dis¬ 
ease that usually attacks a person only once. 4. What is the 
effect of mixing the blood of a typhoid fever patient with typhoid 


28 


The Human Body and Its Enemies. 


bacteria? 5. Will the blood of any healthy individual have the 
same effect? 6. Name one way by which bacteria can be killed by 
the body aside from the stomach and gastric juice. 7. What word 
do we use to describe one who has had measles and cannot have it 
again? 8. What is artificial immunity? ' 9. What physician first 
produced an artificial immunity to prevent a disease, and what was 
the disease? 10. How did he produce the artificial immunity? 11. 
What do we have to introduce into the body in order to produce an 
artificial immunity? 12. Give several ways to weaken disease 
germs. 13. Mention one important fever that can be prevented by 
artificial immunity. 14. Compare the number of cases of typhoid 
fever which occurred among the U. S. soldiers during the Spanish- 
American War with the number of cases occurring during the San 
Antonio encampment. 15. Account for this difference. 16. Which of 
the following diseases are prevented by vaccines, and which by anti¬ 
toxins: Typhoid fever, meningitis, diphtheria, smallpox, cholera, te¬ 
tanus? 17. Why is it important to treat promptly a nail thrust or 
a wound made by powder? 18. What is a toxin? 19. What animal 
do we inject the toxin into in order to form antitoxin? 20. Does 
the immunity caused by the injection of antitoxin into the human 
body last as long as the immunity produced by the injection of dead 
bacteria? 21. Why is smallpox so contagious or so hard to control? 
22. Give some proof that vaccination will prevent smallpox. 23. Give 
the main facts about the two babies shown in the picture. 24. Tell 
how the white cells protect us against disease. 


CHAPTER V. 


Typhoid Fever. 

Typhoid fever is a good deal more like measles than most 
of us realize. It causes a “breaking out,” or rose rash, like 
the rash seen in measles, although there are generally only 
about a dozen or two spots in the skin at 
one time. It is like measles, in that each 
typhoid patient catches the disease from a 
previous typhoid patient, as we shall see 
later. It is like measles, in that it seems to 
affect the young people especially, for old 
people are less often affected. It is 
important to remember, that each typhoid F ^ c f er — 
patient must be carefully handled to avoid Nttie^ la f^ 

giving the fever to some one else. move. 

Importance of Typhoid Fever.—Typhoid fever is a disease 
that is very common in nearly all parts of Texas. It is com¬ 
mon in town and city. Every year there are about nine hun¬ 
dred deaths from typhoid fever reported in our State; and 
yet it is a disease that can be prevented more easily than most 
other diseases. In other words, we can do more good in pre¬ 
venting sickness and death by studying typhoid fever and its 
prevention, than in any other way. Typhoid fever is a con¬ 
tagious disease; see Rule 3, Sanitary Code, page 337. 

Germ of Typhoid Fever. —Now, typhoid fever is due to a 
germ. The germ is a little rod-shaped germ that lives in 
certain parts of the intestine. It also lives in the blood and 
travels all over every part of the body. It injures the entire 
body, but is especially harmful to the intestine, for it causes 
ulcers or raw spots in the intestine. Sometimes these raw 



30 


The Human Body and Its Enemies. 


ulcers are so deep that they cause a hole in the intestinal wall, 
and the patient frequently dies. The hole through the intes¬ 
tinal wall is called a perforation. If the ulcer does not eat out 
a hole entirely through the wall of the intestine, it may still 
cause the patient’s death by bleeding. Such a bleeding is 
called a hemorrhage; in this case it is a hemorrhage of the in¬ 
testine. 

Typhoid Germs Multiply Only in Human Body. —Now, you 
have learned where the germ lives and multiplies. And this 
is, except in milk, the only place in nature where the germ 
multiplies. The typhoid germ does not even live in the lower 
animals, and they do not have typhoid fever. But the typhoid 
germ can live for a few days in water or milk, or it can live 
for a longer time in filth. It can live long enough to be car¬ 
ried to a new patient and cause the disease in him. 

Typhoid Germs in Waste Matter. —No doubt you are won¬ 
dering how the germ can get into the mouth of the new pa¬ 
tient, to be swallowed by him. There are several ways by 
which the germ can pass from the sick man to a well man. 
For instance, the germs are swarming by millions in the un¬ 
clean waste matter that is thrown off by the intestine. When 
we eat any food, the digestible portion of it is dissolved and 
absorbed in the stomach and intestine; but there always re¬ 
mains a certain amount that is not digestible, and hence is 
useless to the body. This passes entirely through the intestine 
and is cast off from the body as body waste. This body waste 
from a typhoid patient is simply alive with typhoid germs. If 
you could see them, you would see that they are more numer¬ 
ous than blackbirds in the biggest flock of blackbirds you 
ever saw. 

Flies Carry Typhoid Germs on Their Feet. —One single fly 
can carry enough of this unclean and dangerous material on 


Typhoid Fever. 


31 



one foot to cause a boy or girl, or even a grown man, to 
take typhoid fever. The fly acts as a messenger between the 
typhoid patient and the well man, and causes the well man 
to become sick. The fly goes out in the back yard, where all 
the unclean body waste from the sick room 
of careless people is poured on the ground. 

He lights on it, and puts his feet in it. The 
fly’s feet are covered with hair, making it 
easy for unclean material to stick to his feet. 

The fly may then pass into the dining room 
or kitchen and walk over the butter, or the 
jelly. Can you imagine how the fly leaves 
a trail of germs behind? The picture shows 
a flat dish of jelly that a fly has crawled 
over. The germs have multiplied for twenty- 
four hours and caused the spots which yon 
see. Anyone eating this jelly now would 

swallow more germs than 
there are people inhabiting 
the United States. If some 
little boy had eaten the jelly 
just after the fly squirmed 
across it, he would have been 
unable to see any trail, but 
would nevertheless even then 
have swallowed more germs 
than the number of inhabi¬ 
tants in your county. 

Do you see how easy it is 
for the germs to pass from 

Fig. 18.—Tracks made when a fly 
walked across a plate of gelatine. a Sick to a Well man? 

Each dot is a colony of germs. 


Fig. 17.—Foot of 
fly, showing how 
it can carry 
germs. 




32 


The Human Body and Its Enemies. 


Typhoid Germs in Drinking Water. —But this is only one 
way. The germs can also reach us by another route, and that 
is in the drinking water. Suppose there is a family living on 
a hill side, with the back yard higher than the front. The 
well will probably be near the house. A great many unclean 
things are thrown on the ground near the well, and as the 



Fig. 19.—Showing a well located in the wrong place. The drainage all 
seeps into the well. 

back yard slopes up the hill, any rain that falls will tend to 
wash these unclean things back toward the well. If the well 
is not cased in at the top with a water tight casing, some of 
the water and filth may drain into the well. A great many 
wells are cased in at the top with rocks or pieces of stone. 
Water can easily trickle through the cracks between the pieces 
of stone. In a loose soil, the germs can soak through the soil 
without being filtered out entirely. The water may contain 
millions of typhoid germs that came from the body waste of 








Typhoid Fever. 


33, 


the typhoid patient. If any one drinks the water of this well, 
he is likely to become ill with typhoid fever in about twelve 
or fourteen days; for it takes about twelve or fourteen days, 
for typhoid fever to develop after the first germs enter the 
body. Hence in trying to trace the source of a case of 
typhoid,we always inquire particularly where the patient was 
about two weeks before taking sick. 

Typhoid Germs in Milk. —Most typhoid is spread in one of 
the two ways described, but there is one other favorite road 
which the typhoid germ likes to travel, and by this we mean 
the milk route, or the dairy route. Dozens of epidemics have 
occurred in which practically all the sick people had been 
using milk from the same milk dealer. Typhoid germs mul¬ 
tiply in milk very rapidly, and a single fly can poison a large 
can of milk. If this be mixed with other milk it will poison 
that, and so there is no limit to the amount of harm that may 
come from germs in milk. 

How the Germs Get Into Milk. —There are several ways the 
germs can get in the milk. It may be from flies. It may be 
from well water used to wash the milk vessels, or it may be 
from the fingers of one of the milk maids or milk men. One of 
the men or women handling the milk may be a typhoid carrier. 

Typhoid Carriers. —And what is a typhoid carrier? A ty¬ 
phoid carrier is a man who has the typhoid germs in his sys¬ 
tem, but who is not sick. Usually a typhoid carrier has had 
typhoid fever at some previous time, and recovered his health, 
and yet the germs have never left his body. This seems hard 
to believe, but is absolutely true. It is easy to see how a man 
could have a few germs in his body after he commenced to 
get well, but the typhoid carrier actually has many gerrAS in 
his body for months or years after he has gotten well from 
his siege of fever. See Fig. 55. 


34 


The Human Body and Its Enemies. 


When you studied the chapter on immunity you learned 
how it is possible for a deadly disease germ to be harmless to 
individuals that are immune. In the case of a typhoid car¬ 
rier, he is immune to the typhoid germ, and cannot be injured 
by it, and yet the germ has the power to live in his body. 
Probably the germ cannot live in his blood, and it certainly 
can do him no harm. 

Typhoid Carriers Give Typhoid Fever to Those Around 
Them. —Just think what terrible damage a typhoid carrier can 
do! Without knowing it, he can give 
this disease to many of the people 
he holds most dear, and to many 
strangers that have done him no 
harm. The United States Army will 
not allow a known typhoid carrier 
to enlist in the army. He would be 
too dangerous to his comrades. But 
not many typhoid patients develop 
into typhoid carriers, and this is 
fortunate. 

Necessity for Washing the Hands 
Frequently. —A great many peo- 
fever germs by shaking hands 
with a typhoid patient, or by handling his bed or clothing. 
Anything a typhoid patient has touched is likely to be soiled 
with the germs. The way to avoid getting the disease in this 
way is to rinse the hands carefully in soap and water, or bet¬ 
ter in an antiseptic solution, after having touched a typhoid 
fever patient. 

Anyone who waits on or nurses a typhoid patient should 
avoid doing the cooking and bread making for the family. 
If it is necessary for her to do so, her hands should be disin- 



Figr. 20.—Washing the hands. 
(This should be done es¬ 
pecially before eating:.) 


pie get the typhoid 


Typhoid Fever. 


35 


fected thoroughly before she enters the kitchen. Now you 
have learned the most important routes for the spread of ty¬ 
phoid fever. There are many other ways that it can be 
spread, as, for instance, by oysters, 
lettuce, radishes and other articles 
of food commonly eaten raw. 

How to Decide the Manner of 
Spread of Typhoid After an Epi¬ 
demic Occurs. —There are certain 
ways we can form an idea as to how 
a given epidemic is spread. This is 
very important, too. 

(1.) The epidemic of typhoid fe¬ 
ver spread by the fly always oc¬ 
curs at a time when flies are plenti¬ 
ful, or, in other words, in warm 
weather. (2) An epidemic spread by the fly usually occurs in 
those parts of town where there are most flies. (3) An epi¬ 
demic spread by flies is never sudden or ‘ ‘ explosive y * in its 
nature, but drags along through the summer, getting a little 
worse as August and September approach, and dying after 
frost falls. (4) In an epidemic spread by flies each case is 
usually near some other case. 

(1.) The epidemic spread by drinking water, if in a town 
with public water supply, usually is explosive or sudden, and 
a dozen or possiby a hundred people will become sick the same 
week. (2) In an epidemic spread by drinking water, cases 
occur in widely separated parts of town. (3) An epidemic 
spread by drinking water usually follows certain cases of ty¬ 
phoid which have occurred upstream along the banks of the 
river supplying the town. 



fork. The typhoid patient 
should keep his separate 
from the family. 





36 


The Human Body and Its Enemies. 


(3.) The epidemic of typhoid spread by milk is likely to af¬ 
fect persons who take milk from a certain dairyman; that is, 
persons affected are all on one milk route. In an epidemic 
spread by milk, children and old people are especially af¬ 
fected, because they use most milk. Such an epidemic is likely 
to affect well-to-do people in cities, because they use more milk 
than poor people; in small towns in Texas, almost all citizens 
are able to get milk, and this point is not noticeable. 

Disinfectants Used to Kill Typhoid Germs. —Now comes the 
important question how to prevent typhoid fever. The most im¬ 
portant thing is to kill all the germs as fast as they leave the 
body of the patient. This is best done by chemicals or drugs 
which are poisonous to germs. We 
call these chemicals “disinfectants.” 
In chapter XVI, on disinfectants, 
you will learn more about how to 
use them. Most disinfectants are 
poisonous to human beings as well 
as to germs, hence their use should 
be left in the hands of grown people. 
All body waste, discharges, secre- 
Fig-. 22.—Hole dug to receive tions > excr etions, and all slops gen- 
?s P to 0i keep a fiils out. he Dis- erall y from tlle typhoid sick room 
iS&° the hoie. ld be poured should be disinfected thoroughly. 

This may be done cheaply with chlo¬ 
ride of lime, with pure or crude carbolic acid, with corrosive 
sublimate, or by patented preparations made from coal tar. 
These are mentioned and described in Chapter XVI. 

Good Method of Disinfection for Country Districts. —A good 
way to do in the country is to dig a hole two feet square and 
two or three feet deep in the back yard, at least one hun- 



Typhoid Fever. 


37 


dred feet from the well. First, disinfect the slops, then 
pour them into the hofe, and have a wooden or wire 
gauze lid to cover the hole to keep 
out the flies. Sometimes the method 
used had best be determined by the 
physician caring for the case. 

Dangers of Carelessness. —If you 
do not disinfect the body wastes 
from the patient, you are scattering 
sickness and death among your 
neighbors. It would be far better.to 
turn loose a box of rattlesnakes in 
your back yard than to pour out 
the body wastes with the living ty¬ 
phoid germs. 

How to Handle the Laundry of a Typhoid Patient. —It is not 

right to turn a lot of typhoid linen over to a wash woman or 

laundry without warning. In hand¬ 
ling the soiled linen, the wash wom¬ 
an or one of the laundry workers 
may get the disease. All soiled linen 
from the sick room should be either 
soaked in a disinfectant solution be¬ 
fore being handed over to the laun¬ 
dry, or should be Wrapped in a clean 
sheet or pillow case, so that the wash 
woman can drop it into a pot of boil¬ 
ing water without touching the 
soiled linen. 

The plates, knives and forks and 
other utensils used by a typhoid patient should be kept sepa¬ 
rate from those of the family, and should either be soaked in 



Fig. 24.—Disinfecting the 
linen. The bundle is 
dropped into boiling water 
without being undone. 



Fig. 23.—The slop-bucket is 
the citadel of typhoid fe¬ 
ver. (When we disinfect 
the body wastes, we 
“head the typhoid germs 
off.”) 



38 


The Human Body and Its Enemies. 


antiseptic solution or placed in a disli-pan of water and boiled. 
These points will naturally be looked after by the physician, 
and in case a trained nurse is in attendance, the physician will 
probably entrust all these things to her. 

Length of Time the Danger of Contagion Lasts. —These pre¬ 
cautions should be kept up until the physician declares the 
patient to be free from typhoid germs. At the present time, 
1912, it is impossible for a bacteriological examination to be 
made in each case, but Texas will not be free of typhoid fever 
till we get into the habit of making these tests regularly in 
all cases. 

How to Avoid Catching Typhoid From Neighbors. —But sup¬ 
pose that the case of typhoid fever is in a neighbor’s family, 
how can we escape catching it? There are several practical 
things we can do. The most important is to use screens and 
sticky fly paper, and wage war on the flies in the neighbor¬ 
hood in every possible way. We must also notice the lay of 
the land, to see if any drainage occurs from our neighbor’s 
premises into our own. If he is on the uphill side of us, we 
must be extremely careful, because a rain may wash his back 
yard, and the washings may trickle into our well. This may 
be good for his back yard, but it is certainly not good for 
our well. If there is a reasonable doubt as to this point, we 
must boil the drinking water. The patented household filters 
are as a rule worthless. Those who object to the flat taste of 
boiled water can restore the taste to it by pouring through 
the air a few times from one pitcher to another. 

When Cistern Water Is Dangerous. —If a cistern be used on 
the premises, it is well to have a care about English sparrows 
and pigeons, which may carry typhoid germs on their feet and 
soil the roof. This point is rather important in towns. 

When typhoid is occurring all around you, it is well to first 


Typhoid Fever. 


39 



see that your dwelling is free from flies; then convince your¬ 
self as to the purity of the drinking water. Then inquire as 
to your milk supply, and your supply of raw vegetables and 
oysters. These sub¬ 
jects are discussed (■ 

more fully in chap¬ 
ters XX. and XXI. 

Those who are go¬ 
ing to take care of 
typhoid patients will 
probably desire in 
some cases to be 
made immune to ty¬ 
phoid fever by anti¬ 
typhoid vaccinations. 

The subject of anti¬ 
typhoid vaccination 
is treated in chapter 
IV. 

Asiatic cholera is a 

very fatal disease, 
due to a little comma- 


Fig. 25.—A very faulty cistern. The birds car¬ 
ry germs from the ground to the roof 
on their feet; the cistern is open and is 
a breeding place for mosquitoes. 


shaped germ, which, like the typhoid germ, is spread by unclean 
drinking water. It is not likely to enter Texas, but after the 
Panama Canal is opened up, it might get a start here. The way 
to prevent cholera is to quarantine those who are sick, and to 
use drinking water which is free from germs. 


Important Points. 

1. Typhoid fever is a definite disease, and one attack is usu¬ 
ally followed by immunity. 








40 


The Human Body and Its Enemies. 


2. There are over nine hundred deaths reported in Texas 
from this cause each year. 

3. ‘ At this time there is no better way to improve the health 
of the people of Texas than by directing our efforts xgainst 
typhoid fever. 

4. The typhoid germ does not multiply anywhere outside 
the human body except in milk. 

5. Typhoid germs always come from the solid and liquid- 
material thrown off from the body. 

6. The fly is the cause of more epidemics of typhoid fever 
in Texas than has been realized in the past. 

7. Drinking water is usually polluted by drainage water 
which runs into the well from the top. 

8. By carefully observing certain facts as described on 
page 39, it is possible to decide with some accuracy whether a 
given epidemic is due to the fly, the water, or the milk of a 
community. 

9. Typhoid germs can live in the body of a healthy man, 
and other people can catch the disease from him. 

10. No patient should handle the public milk or food supply 
of a city for at least twelve months after recovering from 
typhoid fever. 

11. No person nursing a case of typhoid fever should handle 
the milk or food of a family. 

12. The slop bucket is the stronghold of typhoid fever. 

13. Typhoid vaccination is a harmless procedure and is val¬ 
uable in preventing typhoid fever. 

Questions. 

1. Which causes more typhoid fever in Texas, the fly or the 
drinking water? 2. What is a typhoid carrier? 3. When does a 


Typhoid Fever. 


41 


person become immune to typhoid fever? 4. Why is it dangerous 
for a person just getting up from typhoid fever to sell milk? 5. 
Why should the nurse not make the bread for the family in case of 
typhoid fever? 6. After coming from the typhoid sick room what 
should you do before eating? 7. What is the safest way to dis¬ 
pose of the slops out in the country or on a farm? 8. What part of 
the fly is especially likely to carry germs? 9. How do the typhoid 
germs get into milk? 10. Suppose a large mass of decaying vege¬ 
tables and small animals is left near a house, if there were no hu¬ 
man waste material in it, could it cause typhoid fever? 11. How 
many deaths are reported in Texas from typhoid fever each year? 

12. Can we accomplish anything by trying to prevent typhoid fever? 

13. What kinds of unclean material does the typhoid germ live in? 

14. What part of a well is most likely to let the typhoid germs get 
in, the top, the sides or the bottom? 


CHAPTER VI. 


Consumption or Tuberculosis . 

Consumption is such a common disease that some boys and 
girls think they know all about it already. But common as 
it is, there are a great many interesting things about consump¬ 
tion that will surprise you when you hear them. For in¬ 
stance, there are about six people that get entirely well of 
consumption for every one that dies of it. 

Majority of People Have Consumption. —Almost everybody 
that lives to be fifty years old has had consumption at some 
time during his lifetime, and most people never know when 
they have it. At least three out of every four men have con¬ 
sumption before they die. You wonder how we know they 
have consumption if they do not know it themselves. We 
know it because thousands and thousands of bodies have 
been examined after death, and a large majority of them have 
shown at least some scars from an old consumption that had 
healed up. Many of these people, in fact, most of them, never 
dreamed they had ever had this disease. This shows us two 
very important things: it shows us how gradually the dis¬ 
ease can begin, and it shows us how many people get well 
of consumption. 

Of course, you know that the organs most often damaged by 
this disease are the lungs, and that the usual signs of the dis¬ 
ease are a cough that lasts a long time, and loss of weight. 
Most people that cough constantly are consumptives. 

Lungs Are Especially the Seat of Consumption. —The lungs 
are so important in the spread of consumption that we shall 
not study the other organs very much; but yet it is well to 


Consumption or Tuberculosis. 


43 


know that the consumption germ can live in the skin, in the 
intestines, in the bones, in the kidneys, in the coverings of th»} 
brain and cord, and in fact anywhere in the body. By far 
the greater number of cases of consumption, however, are 
consumption of the lungs. We have almost given up the use 
of the word consumption except in speaking of the lungs. 
When we mention the disease in the other organs we give it 
the longer name, “tuberculosis.” We then give the name of 
the organ affected, as, for instance, tuberculosis of the lungs 
or hip. 

The Germ of Consumption. —The germ of tuberculosis is a 
little rod-shaped bacterium. It cannot move, but remains still 
until something blows it or washes it along 
to a new place. The tubercle bacterium can¬ 
not live but a few hours if placed on a pane 
of glass in the sun; it can live a few days 
on the surface of the ground in a sunny 
place; but it can live for weeks and possibly 
months when it is a dark, moist place. It 
does not multiply, however, after it leaves 
the human body. A house that has been oc¬ 
cupied by a careless consumptive that spits 
on the floor is dangerous for months afterward. 

There are other animals that can have tuberculosis besides 
man. Man does not catch the disease, however, from any 
other animals except cattle, that is, cows. Little children can 
get tuberculosis of the intestines or bones or glands from 
tubercle germs in cow’s milk. 

Method of Spread of Consumption. —It is very easy to ac¬ 
count for the spread of consumption, but the wonderful thing 
is that so many escape the disease. Just think of the people 
that have consumption for ten years and go about spitting on 



Fig:. 26.—The grerni 
of consumption, 
called the Tu¬ 
bercle Bacillus. 


44 


The Human Body and Its Enemies. 


the floor, on the sidewalks, on the floor of street cars, and 
even on carpets. The spit dries up and people walk over it, 
and grind it into dust; the wind blows it up into the air, and 

men breathe it into their 
lungs. Worst of all, some peo¬ 
ple aren’t even satisfied to 
leave this dust alone, but 
must take a broom and sweep 
it up dry. Of course, this is 
unwise. Dry sweeping and 
dry dusting in our homes is 
really dangerous. 

Evils of Dry Sweeping. —If 
you were to try to write an 
essay or composition on how 
to spread consumption germs 
you could not possibly think 
of any way to spread them 
which would equal the dry 
sweeping method. If you took an atomizer and put the dust in 
it and attempted to blow it into people’s noses, you would not 
spread the germs nearly so well as by the dry sweeping method. 
You can take a broom and go into a room and raise a dust in 
three minutes that will float in the air for at least an hour or 
two, and will place germs first in the nose of the sweeper, and 
then in the noses of all others who enter the room for a long 
time after the sweeping is finished. And after the dust settles, it 
is there to be stirred up again with the feather duster. When 
you think of this process that is going on in thousands of homes 
in Texas, it is enough to remind one of the sacrifices which the 
Aztec Indians in Mexico used to make. They killed people on 
a big round stone altar. They killed them as a sacrifice to 



Fig:. 27.—The careless consumptive 
spits on the floor; the spit dries 
and is swept up into the air when 
the grirl raises a dust; the baby 
plays on the floor. 






Consumption or Tuberculosis. 


45 


their cruel gods. When we spread consumption, we kill peo¬ 
ple as a sacrifice to our own ignorance or carelessness. 

Aren’t you glad there is a remedy for this? We can stop 
this cruel sacrifice. We have plenty of water to sprinkle the 
floor with, and we can stop spreading consumption in our 
homes at any rate. Besides, it is against the law in Texas for 
any porter or janitor to sweep a public building by the dry 
method, without sprinkling. See Sanitary Code for Texas, 
page 337, Rule 54. 

How to Avoid Raising a Dust. —There are several ways of 
avoiding a dust when we sweep our homes. We should avoid 
heavy carpets on the floor, and should have a floor as smooth 
as possible. Rugs which can be taken out and shaken or 
beaten are not dangerous. If a carpet is in use, it should be 
swept with a carpet sweeper, or, better still, with a vacuum 
cleaner. The floor can be cleansed in several ways. If it is a 
hall, the floor may be oiled, and brushed up with a brush in¬ 
stead of a broom. In the case of a bedroom, with a common 
pine floor, such as we find in the vast majority of Texas homes, 
dampened sawdust may be scattered over the floor before 
sweeping. In some places sawdust is scarce, and pieces of 
newspaper can be dampened and scattered on the floor before 
sweeping. Of course, in all cases, a brush is better than a 
broom. 

In dusting, a rag or cloth should be used, and it should be 
dampened with water or greased with raw linseed oil, so that 
the dust will stick to the cloth. It is not necessary to use any 
antiseptic in the water. See also Sanitary Code for Texas, 
page 337, Rule 54. 

Danger of Feather Duster. —Feather dusters are too danger¬ 
ous to have in a dwelling of human beings. It is all right to 


46 


The Human Body and Its Enemies. 


use them out in the open air to brush the dust off a buggy or 
automobile. But the dust in the houses is dangerous. House 
dust is more dangerous than street dust, for two reasons: in 

the first place, the sunlight of the 
street will kill any germ in a few 
days; and, in the second place, al¬ 
most all disease germs come from hu¬ 
man beings, and around the house 
you find more human beings, and 
hence more disease germs. 

Consumption Spread by Droplets. 
—When a consumptive coughs, he 
blows out a number of little fine 
drops of spit, and these little drops, 
or, droplets are so small that some of 
them float in the air like fog on a 
misty day. For this reason, it is dan¬ 
gerous to have your face close to a 
consumptive when he is coughing or 
even talking. Have you not noticed 
little pieces of saliva or spit leap out 
of a man’s mouth when he is talking ? 

There are a great many little drop¬ 
lets which are invisible, but which 
contain germs, and are dangerous. 

For this reason it is dangerous to 
sleep in the same room with a con¬ 
sumptive. In fact, no consumptive 
ought to sleep in a room at all. He 
ought to sleep in the open air. Don y t ever sleep in the room with 
a consumptive. There is always a way to avoid it, especially in 
our Southern climate, where bitter cold weather seldom comes. 



Fig-. 29.—If possible he 

sleeps in the open air or 
in a window tent. 



Fig. 28.—The careful con¬ 
sumptive sleeps by him¬ 
self. 








Consumption or Tuberculosis. 


47 


Kissing. —A consumptive should never be kissed early in the 
morning until he has washed his face, and even then, not on 
the mouth. Kissing him on the cheek is not dangerous if he has 
washed his face. It is the dust and uncleanliness that are dan¬ 
gerous. At the same time, it is very wrong for a consumptive 
to fondle and kiss a little baby or child on the mouth. 

Consumption Is Not Inherited.— No child ever comes into the 
world with this disease already fastened to him; and yet, inher¬ 
itance is important in connection with consumption. We can 
inherit a set of lungs that will de¬ 
velop consumption if the germs are 
ever put into them. But even then 
we cannot possibly have consumption 
unless we get the germ into our 
lungs. Some men are so fortunate, 
it seems, that even a fair number of 
germs can get into their lungs with¬ 
out remaining there. In some way, 
the lungs are proof against consump¬ 
tion. Others are not so lucky, and as 
soon as the germs get into their 
lungs, the germs multiply and cause 
consumption. These germ-proof men and women are in good 
health, and their strength is up to the standard. In general, 
it can be truly said, that it is harder for any man to take the 
disease when he is strong and in good condition than when he 
is weak and run down or overworked. 

Children Can Get Tuberculosis or Consumption From Milk.— 
Grown people do not catch the disease in this way. But cows 
have consumption, and their milk often contains the germs. 
Babies and children under five using this milk are likely to get 



Fig. 30. The feather duster 
is dangerous and should 
be replaced by the moist 
cloth. See Fig. 36. 







48 


The Human Body and Its Enemies. 


tuberculosis of the bones, of the intestines, or of the lymph 
nodes, such as the kernels along the side of the neck. The cow 
that has tuberculosis may look well. You have probably 
known people who were the picture of health and yet had 
consumption. It is likewise with cattle; it is impossible to tell 
by outward appearances which cows are diseased. The veteri¬ 
nary surgeon can tell, however, by testing the cow. All cows 
that furnish milk for children’s use should be tested by a 
good veterinary surgeon to see. if they have tuberculosis. 

Consumption Is Curable. —Consumption is so plentiful in 
Texas that everyone ought to know something about the 
treatment and outcome of the disease. Consumption is curable. 
At the instant these words are being written, the author is 
seated within six feet of a man that had a severe case of con¬ 
sumption, causing hemorrhages. This was in 1899. He had 
a good physician who diagnosed his disease before he had it 
very long. He went out to the country and lived an out-of- 

door life. He slept out of doors, re¬ 
mained out of doors during the day, 
rested, ate plenty of good rich food, 
and in every way did what his phy¬ 
sician told him to do. The result was 
that he regained his weight and 
strength, and is now back at work 
again, and has been well for five 
years. He says that any educated 
man who wants to can get well of 
consumption. The disease is curable. 
There is no question of that. Prof. 
Irving Fisher of Yale is one of the 
most enthusiastic public health workers in this country, and 
he has fought his way through an attack of consumption. He 



Fig. 31.—The consumptive 
should spit in a rag or 
paper. 


Consumption or Tuberculosis. 


49 


is well now and has been for years. Almost every man can 
point to some friend who has had consumption and recovered. 

There are four things to do in order to get well of consump¬ 
tion : first, sleep and live out of 
doors; second, eat plenty of good 
food like milk, eggs, light bread, 
chicken, fish, and things of that, 
kind; third, rest yourself and save 
your strength, especially if you have 
fever; and, fourth, keep in touch 
with a good physician to advise you 
about any special things that may 
be needed in your particular case. 

How to Prevent Consumption. —If 
we wish to prevent consumption, we 
must be sure that the rent houses 

which we move into are free from 
tubercle germs. Careful inquiry 
should be made in all cases before 
moving into a rent house. Find out 
if anybody has died there in the last 
year. If so, do not expect anyone 
to tell you the deceased died of 
consumption. Some families do not 
like to admit that they have had con¬ 
sumption in any of their number. If 
anyone has died in the house, or if 
there has been any case of sickness 
in the house within twelve months, 
as dangerous and disinfect it. In 
chapter XVI of this book you will find a description of the best 
method for disinfecting a room. 



Fig:. 33.—The rag: may be 
thrown into a disinfectant 
instead of being: burned. 


you had best regard it 



Fig:. 32.—The rag: should be 
burned to destroy the 
•spit. 





50 


The Human Body and Its Enemies. 


Spitting. —We should all be careful where we spit. Every¬ 
one has to spit sometimes, and it is safe to spit in a spittoon or 
cuspidor, on the ground in a sunny place, provided it is not 
on the sidewalk, or in a special paper handkerchief or rag 
carried for the purpose. Those who have tuberculosis should 
carry rags or paper handkerchiefs at all times, and after spit¬ 
ting in them should burn them. See Sanitary Code for Texas, 
page 337, Rule 62. 

The most important thing a family can do to prevent the 
spread of tuberculosis is to stop the dry method of sweeping 
and dusting. 

The Duty of the Government. —The city health department 
in every city should have a map showing the location of each 
case of consumption, and when any house of a consumptive is 
vacated, the house should be disinfected before anyone else 
moves into it. The city should also furnish free printed mat¬ 
ter to the poor who have consump¬ 
tion, so that they may learn how to 
get well, and how to keep from giv¬ 
ing the disease to others. The city 
should have an outdoor hospital, or 
pavilion, for poor consumptives, as 
this would prevent them from 
spreading the germs. Only the larger 
cities can afford to have a visiting 
nurse to go into the homes of the 
poorer consumptives and actually 
teach them how to take care of 
themselves and others. All towns 
should have an inspector to see that the milk sold in the towns 
is pure. This is especially to protect the babies. 



Fig:. 34.—The closed window 
is the friend of the con¬ 
sumption germ, and the 
enemy of good health. 










Consumption or Tuberculosis. 


51 


Important Points. 

1. Consumption is the commonest disease on earth, and a 
large percentage of all people who live to be fifty years old 
have had consumption at some time in life. 

2. Consumption is curable, and a great majority of those 
who have it recover. 

3. Consumption is not hereditary, but is catching; it is 
spread by a rod-shaped bacterium that is cast off from the body 
in sputum: 

4. Tubercle bacteria can live for months in dark corners 
of dwellings, and all rent houses should be disinfected before 
being occupied. 

5. Dusting and sweeping by the dry method is one of the 
ways to spread consumption. 

6. Babies and small children should never drink the milk 
from a tuberculous cow; the only way to be sure a cow is free 
from tuberculosis is to have her tested. 

7. Spitting on the sidewalk is dangerous. 

8. The city government should keep a record of all con¬ 
sumptives and disinfect all houses that have been vacated by 
them. 


Questions. 

1. What percentage of all persons have consumption? 2. Is 
consumption curable? 3. How is consumption spread? 4. Describe 
the tubercle bacterium. 5. Describe the proper method of sweeping 
a room; of dusting. 6. Give several precautions which tend to 
prevent consumption. 7. How long can the germ of consumption 
live in sunlight? In dark corners? 8. What is the danger in mov¬ 
ing into rent houses? 9. Where should a consumptive spit? 10. 
Where should we spit? 11. Is consumption spread by milk? 12. Name 
some things the city government should do to limit the spread of 
tuberculosis. 


CHAPTER VII. 


Golds, Grip and Pneumonia. 

There are a great many disease germs that are so harmful 
to the body that they cause disease as soon as they enter the 
body. Leprosy and consumption are of this kind. You never 
can find leprosy germs or consumption germs in a well man. 
But there are some other disease germs that are not quite so 
harmful to a strong, healthy man, and they can live in his body 
without harming him. The man is so healthy and strong that 
the germs cannot injure him. But if this same man gets wet 
and chilled, especially when he is hungry 
and tired, these germs in his body commence 
to harm him at once. It seems that the germs 
have been waiting for the man to get weak, 
so that they can overcome him. 

The Germs of Colds, Grip and Pneumonia 
Harm Us More When We Are Weak. —The 
germs which cause colds, grip* and pneu¬ 
monia are all of this kind. They are very 
common germs, and almost everyone has 
some of them in his nose and throat all the time. But they 
cannot harm us as long as we are in good condition. If we 
stay out in the open air a great deal, eat plenty of plain, nour¬ 
ishing food, and do not expose ourselves to the weather with¬ 
out proper, warm clothing, the germs are powerless. But if 
we go hunting in rainy, windy weather and stay all day with¬ 
out eating or resting, or if we get our feet wet, especially when 



Fig. 35—The germs 
of grip or in¬ 
fluenza. 


♦Influenza is another name given to grip. 



Colds, Grip and Pneumonia. 


53 


we are tired, the germs may cause a cold or something worse. 

Pneumonia Is Especially Dangerous to Drunkards. —In no 

other disease does alcohol show its damaging effects so plainly 
as in pneumonia. It is a fact well known by physicians that 
.a drunkard cannot withstand pneumonia as well as one who 
does not drink. This is one proof that alcohol can act as a 
poison to the entire system, because pneumonia is not a disease 
of the stomach, but is a disease of the lungs. Alcohol does 
not therefore limit its harmful effects to the organs with which 
it comes in direct contact, but seems to weaken the entire 
system. 

How to Avoid These Diseases. —There are two good ways to 
avoid grip and pneumonia. The first is to keep ourselves in 
good condition all the time. We can do this by regular hab¬ 
its of eating and sleeping, working and playing. We can also 
toughen ourselves by spending a 
great deal of time in the open air, 
and by taking cool baths regularly. 

W^ should start taking the cool baths 
in the summer time, not in the win¬ 
ter. We should also start the habit of 
remaining in the open air in the sum¬ 
mer time. Then, as the winter wears 
on, we can keep it up, within reas¬ 
onable limits. 

This is probably the best way to 
avoid grip and colds, and one good 
way to avoid pneumonia. 

The other way is to try to keep from getting germs from any¬ 
one that is sick. It seems that the pneumonia germs from a pa¬ 
tient with pneumonia are worse than those we find in people 
who are not sick. You know, the pneumonia germ does occur 



Fig - . 36.—A moist rag 

should be used to re¬ 
move dust. 





54 


The Human Body and Its Enemies. 


in the noses and throats of healthy people. But these do not 
seem to be so harmful as the germs from an actual case of 
pneumonia. The same is true of grip. Many people who 
seemed strong and well have caught pneumonia and grip by 
going into the sick room, and, therefore, no one should enter 
the sick room except for some good reason, and the hands 
should always be washed afterward. These people have not 
done anything to weaken themselves, and yet the germs over¬ 
came them. 

The Value of Fresh Air. —Plenty of fresh air in our living 
and sleeping rooms helps a great deal in keeping our strength 
up to the standard. Fresh air also helps the patient who has 
pneumonia, but this will be looked after by the doctor. 

Care of the Hands; Linen; Sweeping and Dusting; Plate, 
Knife and Fork. —Everybody should know, however, that cer¬ 
tain precautions should be taken around any sick room. For 
instance, the linen from the patient and his bed should not be 
handled or flirted in the air, but should be carefully bundled 
up and dropped in boiling water or in a disinfectant solution, 
as shown in Fig. 24. Those who have to care for the patient 
should always wash their hands carefully after leaving the 
room, especially before eating. Dusting and sweeping by the 
dry method should not be done in the sick room, or in fact in 
any room. A separate plate, knife and fork should be set aside 
for the use of the patient, and should be kept separate from 
those used by other members of the family. 

Important Points. 

1. The germs of pneumonia, colds and grip are frequently 
found in the air passages of healthy persons. 

2. Exposure to wet and cold weather upsets the body of 


Colds, Grip and Pneumonia. 


these persons slightly and enables the germs to multiply 
and produce toxins and cause disease. 

3. In other instances, the germs of any of these three dis¬ 
eases seem to attack strong, healthy persons who have not been 
exposed to cold weather. 

4. We can avoid these diseases in two ways: first, by 
keeping ourselves strong, so that the germs cannot overcome 
us; and, secondly, by keeping away from persons sick with 
these diseases. 

5. In the sick room the usual precautions should be taken, 
as follows: a separate set of eating utensils should be kept 
for the patient; the linen should be handled cautiously; dust¬ 
ing and sweeping should be done by the moist method; all per¬ 
sons entering the sick room should wash their hands afterward. 

Questions. 


1. Name some germs that cause disease whenever they enter 
the human body. 2. Name some germs which sometimes live in the 
human body without causing disease. 3. Suppose you have the 
germs of grip in your system; tell how you could bring on an attack 
of grip. 4. Does the germ of pneumonia or grip ever act like the 
typhoid germ, and cause illness in a strong, healthy person? 5. Give 
three precautions to remember in the sick room. 6. If alcohol is 
taken into the stomach instead of the lungs, why does it injure 
the lungs? 


CHAPTER VIII. 


Meningitis and Diphtheria. 

Meningitis and diphtheria are, in some respects, like the 
diseases discussed in the preceding chapter, for they are due 
to germs which can live in the human body without causing 
illness; but the germs of diphtheria and meningitis are not 
often found in the nose or throat of healthy people; it is more 
unusual for this to happen than in the case of the diseases 
treated in the preceding chapter. Diphtheria and meningitis 
are very contagious and very dangerous. 

Diphtheria Is a Dangerous Disease. —Diphtheria caused al¬ 
most as many deaths in the United States in 1910 as typhoid 
fever, but in- Texas it causes only about a fourth as many 
deaths each year as typhoid fever. In 1911, diphtheria caused 
two hundred and eighty-one deaths in this 
State; diphtheria stood sixth among the 
communicable diseases as a cause of death. 

How the Diphtheria Germ Injures the 
Human Body. —The diphtheria germ lives in 
the nose and throat. It may cause the mu¬ 
cous membrane to swell and stop up the 
throat so that the patient cannot get his 
breath, or the germ may form poisons or tox¬ 
ins in its body. These toxins are absorbed 
into the blood and may be carried to the brain and stop the 
heart from beating. It is the toxins made by the diphtheria 
germs which cause the patient to have fever and flushed cheeks. 

Diphtheria Antitoxin Cures if Given Early. —It is indeed for¬ 
tunate that we have such an excellent remedy against dipli- 



Fig. 37.—The germ 
of diphth e u i a; 
this germ is cast 
off from the 
the body in spit 
and on the pock¬ 
et handkerchief. 



Meningitis and Diphtheria. 


57 


tlieria. You have learned in a previous chapter something 
about how antitoxin is made. The diphtheria antitoxin is made 
from the blood of a horse that has been specially treated with 
toxins of diphtheria germs. This serum or antitoxin almost 
always cures the cases in which it is given early, and for this 
reason it is well to have all sore throats examined, so that if 
diphtheria is present, no time will be lost. 

Prevention Would Be Better Than Cure. —It may be on ac¬ 
count of the fact that we have this excellent cure for diph¬ 
theria that so few precautions are taken to prevent the spread 
of the disease. While the death rate from the disease has been 
lowred by the treatment with serum, there are still far too 
many cases of the disease. It would be much better to prevent 
the disease than to cure it. 

How to Prevent Diphtheria. —The most effective way to pre¬ 
vent diphtheria is to isolate all cases of the disease until they 
are well and the germs have left their 
throats, for it has been found that the 
germs live for some time in the throats of 
patients after recovery. For this reason, 
wherever possible, an examination of the 
throat should be made before allowing a 
patient to go about in public. It is not al¬ 
ways practical to do this, however, and 
the doctor will have to use judgment in 
letting the patient go. 

Seeing that healthy boys and girls can 
carry the germs around in their noses and 
throats without knowing it, it is wise to 
avoid using the common drinking cup, and the common or pub¬ 
lic towel. One should also avoid borrowing pencils and things 
of that kind from others, for many people have the foolish 



Fig. 38.—All public 
towels should be of 
paper and should be 
used only once be¬ 
fore being thrown 
away. 







58 The Human Body and Its Enemies. 

habit of moistening their pencils in their mouths. The diph¬ 
theria germs do not multiply outside the body, except when 
some careless person allows them to get into milk. They always 
come from the human body. 

Meningitis Is an Inflammation of the Coverings of the Spinal 
Cord, and it is due to a little oval germ which lives in the nose 
and throat and spinal canal of those who are sick. We call 
this little germ the “meningococcus,” and 
as you can see in Fig. 39, it occurs in pairs. 
You can see in the picture that the white 
cells of the blood have swallowed some of 
the meningitis germs. 

Epidemic Meningitis Is Due to a Little 
Oval Germ. —The spinal cord is composed of 
rig. 39.—w h i t e nerves and nerve cells, and is almost like a 

blood cells con¬ 
taining m e n i n- part 0 f the brain, as you will see later. It is 
gitis germs. ^ J 

well protected by tough coverings, and it is 
on these coverings that the meningitis germ especially likes to 
live. The germ causes inflammation of the coverings of the 
cord. It is not the only germ which can live in this position 
and cause this inflammation, but it is the only germ which 
causes these symptoms in epidemic form. It seems that the 
meningitis germ has a preference for this location, and does 
not cause disease elsewhere in the body. When other germs 
attack the coverings of the spinal cord it is almost always in 
the course of a spell of sickness in which other parts of the body 
are affected also; the typhoid germ, for instance, can affect the 
coverings of the cord and in a sense cause meningitis, but the 
typhoid germ never causes epidemics of meningitis. 

Healthy Persons Sometimes Carry the Germs of Meningitis.— 
It seems altogether probable that the germ of meningitis can 
live in the nose and throat of a healthy individual without 




Meningitis and Diphtheria. 


59 


causing any inconvenience. From this person’s throat the germ 
can spread to other people and cause meningitis. 

The Meningitis Germs Enter Our Body Through the Nose 
and Mouth. —For this reason all those who have been close to a 
meningitis patient should be very careful, for they may be 
carriers of meningitis, although they are not sick. 

Value of the Serum Treatment of Meningitis. —Before the in¬ 
troduction of the serum treatment of meningitis, almost all 
persons who had it died; and those who did not die were usu¬ 
ally blind, crippled or otherwise injured. Since this treatment 
commenced to be used, more than half the patients recover, and 
it is rare to find any serious defects as a result of the disease. 
Even now, however, meningitis is one of the most dangerous 
diseases known. Probably it is the most dangerous epidemic 
disease that ever affects our country. 

How to Prevent Meningitis. —The best measures to prevent 
meningitis from spreading are the isolation of the sick, and 
the use of sprays in the nose and throat to destroy the germs. 
All those who have been around a case of meningitis should 
keep their throats sprayed out in order to protect themselves 
as well as others; for one who feels perfectly well can carry 
the germs and spread the disease. 

Certain other germs can cause meningitis but not in epi¬ 
demic form. 

Important Points. 

1. Diphtheria is a dangerous contagious disease of the nose 
and throat, and is due to the diphtheria germ. 

2. The diphtheria germ itself does not spread over the body, 
but its toxins do, and the toxins cause the fever and other 
symptoms of diphtheria. 


60 


The Human Body and Its Enemies. 


3. Diphtheria can be cured by the serum or antitoxin, if it 
is used early. 

4. The secretions from the nose and throat contain the 
diphtheria germ, and therefore public drinking cups and pub¬ 
lic towels are dangerous. 

5. Meningitis is the most dangerous epidemic disease which 
occurs in our State. 

6. It is due to a germ which lives in the coverings of the 
spinal cord, and also in the nose and throat. 

7. Meningitis is spread in the same manner as diphtheria, 
by secretions from the nose and throat. 

8. In both diphtheria and meningitis the germs can live 
in the nose or throat of a healthy person without causing in¬ 
convenience. 

9. The serum treatment of meningitis has cut in half the 
death rate from this disease. 

10. If there is no other way to save life, animal experi¬ 
ments are just and right. 

11. Diphtheria and meningitis are prevented in the same 
way: isolate the sick; avoid handling articles like public drink 
ing cups and public towels; remember that healthy persons 
may be disease carriers. 


Questions. 

1. Where do the germs which cause diphtheria and meningitis 
enter our body? 2. How does the diphtheria germ injure us? 3. 
What is a diphtheria carrier? 4. What is the cure for diphtheria? 
5. Explain how the common drinking cup spreads diphtheria. 6. 
What is the most dangerous epidemic disease which occurs in 
Texas? 7. Where does the meningitis germ enter the human body? 
8. What is the cure of meningitis? 9. What symptoms formerly 
followed meningitis if the patient recovered? 10. Would it be dan¬ 
gerous for the nurse in charge of a meningitis patient to mingle in 
a crowd of people? Why? 


CHAPTER IX. 


Malaria, Yellow Fever and Dengue. 

Malaria, or “chills and fever,” is just as definite a disease 
as measles, and we know more about it than we know about 
measles. We know the little germ that lives in our bodies and 
multiplies, causing malaria; its name is the malarial parasite 
or plasmodium of malaria. The little germ cannot live any¬ 
where in the world except in two places : first, in certain parts of 
the human body, especially 
in the blood; and, secondly, 
in a certain variety of mos¬ 
quito. And the malarial 
germs cannot even live in all 
parts of the human body. For 
instance, if we accidentally 
swallowed or breathed in 
some of the germs they 
would not live, but would 
die in our bodies, and hence would do us no harm. If we drink 
water containing the “wiggle tails,” which are only young 
mosquitoes, it cannot cause malaria. In fact the malarial 
germ is a very particular little germ, and if it cannot enter our 
bodies just as it likes, it cannot live, but dies quickly. 

How the Germ Enters Our Bodies. —How then does the germ 
of malaria get into our body? It comes in through the mos¬ 
quito’s “bill” when she bites us on the skin. And that is 
the only way it ever enters our bodies. Now, it is strange, 
but true, that a malarial patient cannot give malaria to any¬ 
one else unless the mosquito acts as a messenger or car- 



Fig\ 40.—Observe that the mala¬ 
rial mosquito stands out from 
the wall. 





62 


The Human Body and Its Enemies. 


rier to others. In other words, if one member of the fam¬ 
ily has malaria, it is perfectly safe for him to remain in 
the same room with the others, so long as he uses a mosquito 
bar or net to keep the mosquitoes from reaching him. 


these investigations. 


Proving That Malaria Is Spread Only by the Mosquito.— 

The first man to prove that the germs of malaria grow and de¬ 
velop in the mosquito was Dr. Ronald Ross of England, who 
made this discovery on August 29th, 1897. Two years later 
our U. S. Army Commission proved at Havana that yellow 
fever also is spread by the mosquito, and in no other 
way. In Chapter III, you have already learned that 
Dr. Carroll and Dr. Lazear lost their lives while making 
This was in 1900. The same year 
Dr. Wm. Thayer of Baltimore and 
Dr. Albert Woldert of Texas demon¬ 
strated that in this country the Ano¬ 
pheles mosquito harbors malarial 
parasites and by injecting them into 
man, spreads chills and fever. 

While our American scientists 
were making these brilliant discov¬ 
eries, Drs. Sambon and Low of Lon¬ 
don spent the summer in the Italian 
Campagna Swamp, near Rome, 
where almost everyone had malaria 
during the summer. These gentle¬ 
men, however, slept behind mosquito-proof screens, and as you 
will imagine, they remained free from malaria. 

Where the Mosquito Gets the Germs. —But we must not for¬ 
get one thing: the mosquito is harmless unless she has previ¬ 
ously bitten a patient sick of malaria. We say, mosquitoes 
carry malaria from one man to another. If the mosquito could 



Fig. 41.—The malarial mos¬ 
quito, called “Anopheles.” 
This mosquito stands out 
from the wall when it 
alights, as shown in Fig. 
40. 


Malaria, Yellow Fever and Dengue. 


63 


think and talk, she might say, “Human beings carry malaria 
from one mosquito to another.” One man cannot give malaria 
to another without the mosquito, who acts as a messenger or 
carrier. The mosquito is fond of human blood. She thrusts her 
bill down into the skin of a malarial patient deep enough to 
suck out some of the blood, together with the malarial germs 
present in this little drop of blood. The malarial germs multi¬ 
ply in the body of the mosquito. Then later, when she bites some 
other human'being, the germs leave her through her “bill” and 
enter the body of the unfortunate human being, who then 
becomes sick with malaria. 

Prevention of Malaria. —When we limit the number of mos¬ 
quitoes, we prevent malaria. The best method of eliminating 
the mosquitoes is to kill the wigglers 
by pouring oil over the water in 
which they live, or, better still, to do 
away with all standing water, as is 
fully discussed in Chapter XIV. 

Screens Will Prevent Malaria.— 

There is something, however, which 
we can all do that will almost surely 
protect us from malaria; that is, to 
screen our homes. In Texas we have 
such a delightful climate and so lit¬ 
tle really cold weather that we need 
screens all the year round to protect 
us from insects. Copper or brass 
wire screens are most durable but 
expensive. Galvanized iron wire 
screens are next best. Ordinary wire screens do not last long. 
All the screens should be fine meshed, so as to keep out all 
small mosquitoes, too. The variety of screen that has sixteen 



Fig:. 42.—Note that all doors 
and windows are screened 
and that the upstairs 
porch is entirely screened 
in. This house is safe 
from malaria in any cli¬ 
mate. 



64 


The Human Body and Its Enemies. 


meshes to the inch is best. Mosquitoes easily crawl through 
the twelve mesh screens, or through mosquito bars with 
coarse mesh. Mosquitoes may also be driven out of the 
house by burning certain things in a room, so as to cause 
a dense smoke, as, for instance, chips, leaves, or pieces of 
old cotton cloth. The fumes from burning sulphur or in¬ 
sect powder will kill mosquitoes. Whenever sulphur is 
burned indoors, it should be borne in mind that the fumes, if 
inhaled, are irritating and dangerous. Burning sulphur also 
has a tendency to sputter, and in this way leap out of the 
bucket or tub and set fire to the house. Of course, the fumes 
of sulphur will tarnish metals, and hence metal articles of 
value should be taken from the room before fumigating with 
sulphur. 

Old-fashioned Ideas. —Malaria cannot be spread by damp 
air or by the beautiful mists which rise over the swamps and 
may be seen early in the morning. A home in the swamps or 

river bottoms can be ren¬ 
dered perfectly safe from 
malaria by screens and mos¬ 
quito bars or netting; for ma¬ 
laria is a disease that is 
spread in one way, and only 
one, and that is by the mos¬ 
quito. 

Other Diseases Spread by 
the Mosquito. —There are 
two other diseases which are 
also carried by the mosquito, 
namely yellow fever and dengue fever. 

Each Disease Is Spread by a Separate Kind of Mosquito.— 
It is remarkable that only certain kinds of mosquitoes can 









Malaria, Yellow Fever and Dengue. 


65 


carry these diseases, and a certain particular kind of mosquito 
carries each separate disease. One kind of mosquito, called An¬ 
opheles, carries malaria; another kind, called Stegomvia, carries 
yellow fever, and another kind, called Culex, carries dengue. 
The pictures show the three kinds. But, remember, the mos¬ 
quito cannot carry the disease unless she has bitten some one 
sick of the disease. 

Yellow fever is a very fatal disease, and in olden times it 
was much dreaded by people in Texas, because when it oc¬ 
curred in epidemics it would kill many people. The people 
thought it was due to “something in the atmosphere,” or 
‘something that blows up from the swamps.” They were right, 
for that “something” was simply a mosquito. Nowadays we 
know how to stamp out the disease because it cannot be carried 
in any way except by the mosquito. Yellow fever is not so much 
dreaded now as it was formerly. And yet, we are so close to 
Mexico and Cuba and Brazil that once in a while some ship 
will steam into our Texas ports with yellow fever on board. 
When this occurs we can prevent the spread of the disease by 
killing all mosquitoes on board. It does no good to quarantine 
against yellow fever, because you cannot quarantine against the 
mosquito. And if a yellow fever patient enters town he 
could not give the disease to any one if he tried except by 
mosquitoes. Of course, if a town does not rid itself of mos¬ 
quitoes, then a quarantine is needed. 

Dengue is an unpleasant disease to have, but not a danger¬ 
ous one. About every ten years it tries to get a foothold in 
Texas, and sometimes it sweeps all over those parts of Texas 
where mosquitoes are most abundant. It has occurred so many 
times while there was also an epidemic of yellow fever, that 
some people formerly thought it was kin to yellow fever. It is 
an entirely different disease, however, and an attack of yellow 


66 


The Human Body and Its Enemies. 


fever does not protect one from dengue. There were thousands 
of cases of dengue in Texas in the late summer and fall of 1907, 
and the disease did a great deal of harm by leaving 

people weak and nervous, and also 
by frightening them. To pre¬ 
vent another epidemic, each city 
and town should have a health de¬ 
partment to destroy the breeding 
places of mosquitoes. All homes in 
Texas should be screened also. 

Important Points. 



dengue. 


1. Malaria is due to a germ which 
lives half its life in the blood of a 
malarial patient and the other half in the body of a certain 
kind of mosquito. 

2. Malaria will disappear from Texas when all our people 
commence using screens and mosquito bars. 

3. Yellow fever and dengue fever are also spread by the 
mosquito, but each one by a different kind of mosquito. 

4. Only the female mosquito bites man. 


Questions. 

1. What, connection has malaria with the location of a house? 2. 
Name two ’places where the malarial germ lives. Does it live any¬ 
where else? 3. Suppose you should swallow the eggs of a mosquito, 
would you be likely to have malaria? 4. If you drink water from 
a cistern in which there are wigglers will it give you malaria? 

5. Suppose you were bitten by a hundred mosquitoes, none of which 
had bitten a malarial patient, would you contract malaria? 

6. Name two other diseases caused by mosquitoes. 


CHAPTER X. 


Quarantinable and Reportable Diseases. 

One very old method of limiting the spread of a communi¬ 
cable disease is by quarantine. The word quarantine is from 
an old Italian word meaning “forty,” and refers to the num¬ 
ber of days ships were 
held if they contained 
people sick of conta¬ 
gious disease. Today the 
word quarantine usu¬ 
ally means confining 
people to certain prem¬ 
ises or places to stop the 
spread of communicable 
diseases. 

Modern Quarantine— 

Our ideas of quarantine 
have changed as we 
have lear n e d more 
about the cause and spread of diseases. For instance, in small¬ 
pox, we still hold the patient in quarantine a certain number 
of days after he recovers from smallpox; but in diphtheria, as 
you have learned, the germ can live in the throat for some 
time after the patient recovers, and so we do not keep the 
patient for a definite number of days, but keep him until his 
throat is free from diphtheria germs. Sometimes this is a few 
days after the attack is over, and sometimes it is six months. 
For this reason many people are allowed to go free sooner 
than they otherwise would have been, because their throats 
contain no germs; but other patients are kept much longer 
















68 


The Human Body and Its Enemies. 


than formerly, because if permitted to go about in public they 
would be dangerous to the public health. 

While this is so, we still have to rely on a definite time limit 
in many diseases. The following diseases are declared by law 
to be quarantinable in Texas: Asiatic cholera, plague, typhus 
fever, yellow fever, leprosy, smallpox, scarlet fever, diphtheria 
(membranous croup), epidemic cerebro-spinal meningitis, den¬ 
gue, typhoid fever, epidemic dysentery, trachoma, tuberculosis 
and anthrax (charbon). (See Sanntary Code, Appendix B). 

The length of time patients are held varies with the differ 
ent diseases, and depends on the length of time such patients 
continue to be contagious after the recovery from the illness. 

People Who Have Been Exposed to a Disease May Be Quar¬ 
antined. —Sometimes well people are quarantined because they 
have been exposed to a disease, and it is feared they may de¬ 
velop the disease. In this case the length of time they are kept 
under quarantine depends on how long it takes the disease to 
develop after one has been exposed. This period, while the 
disease is developing, is called the incubation period, from the 
fact that the germs are being incubated in the body. After the 
germs are introduced it takes them several days usually to mul 
tiply sufficiently to cause symptoms of disease. Even before 
symptoms develop, however, such patients can convey the 
disease to other people. 

Reportable Diseases. —We should especially note that the 
law requires reports to be made and complete records to be 
kept of all quarantinable diseases, including typhoid fever and 
tuberculosis. The physician in attendance on these cases is 
required by law to report them to the local health officer; the 
latter reports them to the State Board of Health, and both the 
local and the State health officers keep a record. The records 
of cases of tuberculosis are required by law to be kept pri- 


Quarantinable and Reportable Diseases. 69 

vately, and no one except the proper authorities have the right 
to see them. This is done because no outsider has any right to 
know what a patient is suffering from except the officers of 
the law who are protecting the public health. At this time 
there are so few cases of these diseases in many communities in 
Texas that complete records are not kept. As our State grows, 
however, it will be more and more necessary to observe the 
law, and we need improvement in this regard even now. In¬ 
vestigate and see if these diseases are 
reported in your community. If they 
are not, make up your mind to do 
your part in future and get them re¬ 
ported. 

The Sanitary Code Will Be Sent to 
Your School. —The State Board of 
Health at Austin will take pleasure 
in sending to your school a copy of 
the Sanitary Code, containing many 
of the legal rules concerning quaran¬ 
tine and health matters generally. It 
would be well for each class to get a 
copy of this, as it is the law of the 
land. Is it well enforced in your 
town or county? Good citizens should 
be willing to submit to quarantine whenever they have a com¬ 
municable disease, even though it be in a mild form; because 
fatal cases may arise from very mild ones. The Sanitary Code 
for Texas is given in abbreviated form in Appendix B, page 
337, of this book. 

Flagging the House. —As a rule, quarantine consists in keep¬ 
ing the sick individuals in a certain room or house, and pre¬ 
venting any one from entering or leaving this room or house 


TEXAS STATE BOARD •'HEALTH 

Sanitary Code 
Tvxact 



March 2*1-,Wll 


J 


Fig-. 52.—This code is the 
Likw in Texas. (See page 
337.) 








70 


The Human Body and Its Enemies. 


except the nurse and physician, who take pains not to convey 
the disease. A placard is tacked upon the house warning 
the public not to enter, or a yellow flag is placed on the house. 

Elsewhere in this book you have learned what the following 
diseases are and how they are carried from one patient to 
another: Asiatic cholera, plague, yellow fever, diphtheria, 


dengue, men¬ 
ingitis, ty¬ 
phoid fever, 
t uberculosis, 
trachoma 
and anthrax 
(cha r b o n). 
We will take 
up in order 
the follow¬ 
ing commun¬ 
icable dis¬ 
eases, name¬ 
ly : t y phus 
fever, lepro¬ 
sy, smallpox, 
scarlet fever. 


t 



Fig:. 53.—A house under quarantine. The sign on the 
porch is usually omitted. The flag is red or yellow. 


Typhus fever is another name for jail fever, or ship fever, 
and is not closely related to typhoid fever. It exists at all 
times in Mexico, and is found in unclean houses. It is carried 
by certain insects that live in the clothing or hair of uncleanly 
people. These insects are called body lice, or head lice. It is 
not likely that this disease will gain much foothold in Texas. 

Leprosy is a very old disease, and one that is very terri¬ 
fying to most people. It is due to a germ that resembles 
the tuberculosis germ, and is found in the sores and in the 




Quarantinable and Reportable Diseases. 


71 


secretions from the nose of lepers. It is not likely to attack 
many people in Texas. 

Smallpox is a dangerous disease that causes fever and little 
pus pockets or pustules all over the skin of the body. It is one 
of the most contagious diseases known, and a high percentage 
of those exposed take the disease. 

In Fig. 14 you have seen the picture of a little baby with 
smallpox, and a very dismal picture it is. Up to this time, the 
germ of smallpox has never been proved to have been discov¬ 
ered, but, fortunately, this is one disease which we know how 
to prevent. Vaccination is a sure preventive of smallpox. 

Scarlet fever is just another name for scarlatina. There is no 
difference between the two. This disease is very contagious, 
and the garments of a scarlet fever patient retain their power 
to cause the disease in another child for many months. Up to 
this time we do not know the nature of the germ that causes 
scarlet fever, and so we can do very little to prevent the fever 
except to quarantine all scarlet fever patients. The great¬ 
est care is necessary in destroying or disinfecting all toys, 
clothing and other things of this kind that have been in the 
room with a scarlet fever patient. 

Diseases Which Exclude Children From School. —There are 
several diseases that affect children especially, and which are 
so mild that a quarantine is not considered necessary. These 
diseases are measles, mumps, whooping cough and chicken pox. 
These diseases are alike in that they attack a large percentage 
of all children in this country. If one escapes these diseases, 
however, and grows up, he may have the disease after he is 
grown. They are all more or less mild, as a rule, and do not 
kill a high percentage of those affected. Owing to 
the fact that so many people have them, however, these dis¬ 
eases are very important. For this reason pupils are debarred 


72 


The Human Body and Its Enemies. 

from school while sick with either of these four diseases 
mentioned. 

Measles is by far the most important of these diseases. It 
causes every year about six thousand deaths in the United 
States. In Texas alone two hundred and twenty-two deaths 
from measles were reported in 1911. 

Recently it has been noticed that measles is more fatal among 
children from six months to five years old than among boys 
and girls from five to fifteen years old. This would lead moth¬ 
ers to be careful to prevent their children from having measles 
before they reach the age of five or ten. It is not uncom¬ 
mon to hear mothers say that they want their children to have 
measles and get through with it. But this is not wise, for 
measles is a serious disease, especially among little children. 

Whooping cough is also a serious disease when it attacks 
babies and very young children. This disease is due to a defin¬ 
ite bacterium 
t h a t resem¬ 
bles the grip 
germ. The 
wh ooping 
cough germ 
cannot easily 
be carried in 
the clothing, 
but is usu- 
a 11 y spread 
from one 
child to an¬ 
other by di- 

Fig. 54.—Little children should not be allowed to min- r CCt contact 
gle on the street with other children, as whooping „ 

cough and other diseases are caught in this way. utuween tne 

































Quarantinable and Reportable Diseases. 


73 


children. For this reason it is not hard to ward off whooping 
cough. Simply keeping babies away from other children ex¬ 
cept those known to be healthy is all that is needed. Whoop¬ 
ing cough, measles and scarlet fever each cause about the same 
number of deaths each year in the United States. Of course, 
measles is the mildest of the diseases, and scarlet fever is the 
severest. 

How These Diseases Are Spread. —In each of these diseases, 
it is true that some solid or liquid particles must pass from the 
body of the sick into the body of the well before the disease 
can spread. In these instances the particles are especially 
the little droplets of saliva that fly out of the mouth when the 
patient coughs or speaks. In measles and scarlet fever it 
may be that the dried particles of skin that scale off are con 
cerned in the spread of the disease. The germ of measles 
and scarlet fever have never been found, and it is possible that 
they are so small that they are invisible with our strongest 
microscopes. You have already learned that some germs are 
so small that they cannot be seen at all, as, for instance, the 
germ of rabies or hydrophobia. 

Important Points. 

1. Quarantine is an old-fashioned method of preventing 
the spread of disease, and in some cases we have learned a 
better way; but in many cases we still have to resort to quar¬ 
antine till we have found out exactly how the diseases are 
spread. 

2. The laws of Texas declare that the following diseases 
are quarantinable: typhus fever (not typhoid), Asiatic cholera, 
plague and yellow fever, smallpox, scarlet fever, diphtheria 
''membranous croup), dengue and leprosy. 

3. The following diseases are quarantinable only to the 


74 


The Human Body and Its Enemies. 


extent that they debar pupils from school: measles., mumps, 
whooping cough and chicken pox. 

4. The contagion of smallpox and scarlet fever, that is, 
the little particles thrown off from the patient’s body, live 
for many months and retain their power to cause the disease. 

5. The contagion of measles and that of whooping cough 
do not live over two weeks, as a rule, but these diseases are 
dangerous to small children and babies. 

Questions. 

1. What is the old or original meaning of the word quarantine? 
2. Why do we not hold all dangerous contagious cases exactly forty 
days now? 3. Name three quarantinable diseases that have occurred 
in your community. 5. Name two quarantinable diseases in which 
the contagion will live a long while on clothing. 6. Is it wise for 
mothers purposely to expose little children to the measles? 7. How 
many deaths occurred in Texas in 1911 from measles? 8. Name 
three diseases that should exclude pupils from school, but which 
are not of sufficient importance to require a full quarantine. 9. What 
is the best way to prevent whooping cough in babies? 10. Why is 
it important to postpone the attack of whooping cough till the child 
gets older? 11. How can you get a copy of the sanitary code? 


CHAPTER XL 

Pellagra mid Hookworm Disease. 

A great deal of attention has been paid in recent years to 
hookworm and pellagra, two diseases that may be called new 
in the United States. 

Pellagra, a Disease of Unknown Cause. —In Texas more at¬ 
tention has been paid to pellagra than to the other, although 
hookworm disease is probably more prevalent and certainly 
more easily surable than pellagra. Not knowing positively 
the cause of pellagra, we can do nothing to prevent it. It is 
not very catching, if at all, and yet we ought to be careful 
about stating that it is not catching till we know more about 
the cause. It certainly seems, however, that it does not 
spread by contagion, at least in hospitals. No precautions 
have usually been taken to prevent its spread, and yet in 
this State no case has ever caused a second case among the 
nurses or physicians and others who have cared for the pa¬ 
tients. At the same time, there have been several fami¬ 
lies in which more than one case occurred. The main 
symptoms of pellagra are sunburn on the back of the 
hands, the face and neck, with diarrhoea, and nervousness. 
Many cases of pellagra get well, and if medical attention is 
sought early, no one should be discouraged on account of this 
disease. A change to a cool climate is probably beneficial. 

Hookworm Disease Is Present in Texas. —Hookworm disease 
is not uncommon in the thickly settled parts of Texas, espec¬ 
ially in the sandy soils of East Texas. It is a curable and 
preventable disease. 

The Hookworm That Causes This Disease Lives in the Small 
Intestine, and Sucks Blood From the Intestinal Wall. —The dis- 


76 


The Human Body and Its Enemies. 


ease shows itself especially by the lack of blood which is ob¬ 
served in those who have it. These people who have hookworm 
disease are usually pale, weakly and stooped. They lack en¬ 
ergy and strength. They are often nervous and have fickle 
appetites. But, after all, no especial symp¬ 
tom is caused by the hookworm that is not 
caused also by other diseases causing Aveak 
blood. 

The Only Way Surely to Know Whether 
Anybody Has Hookworm Is by the Use of 
the Microscope. —The worms lay eggs, and 
these eggs leave the intestines in the waste 
matter that is thrown off from the body. 
The eggs are too small to be seen with the 
eye, unless the microscope be used. 

The hookworm itself is a small worm about 
a half inch long, and it remains in the in¬ 
testine. The eggs, however, pass out, and 
are dangerous, as they cause the spread of 
the disease. Just how the eggs hatch out and 
get into man’s body is a wonderful story. It 
almost surpasses belief, but we are forced to believe it, because 
there are actual photographs showing the worm in all the 
stages of its journey from one man to another. The egg 
hatches soon after it leaves the body or intestines of the pa¬ 
tient. A little worm is formed from the egg. This worm gets 
on the skin of children, especially those that go barefooted, and 
goes into the skin, causing a little blister where it enters. This 
blister is known as the “ground itch.” We know now that 
ground itch is nothing but one stage in hookworm disease. The 
worm passes through the skin and gets into a blood vessel. It 
passes up the blood vessel to the lungs. Here it eats its way 



NATURAL SIZE 

Fig-. 49. Male and 
female hookworm 






Pellagra and Hookworm Disease. 


77 


through the blood vessel wall and gets into a bronchus, or 
bronchial tube. The worm squirms along the bronchial tube 
and gets to the windpipe and then to the throat. It then 
turns back down the throat and passes through the stomach 
into the intestine, where it commences its usual life. It is 
probable that some hookworm eggs are swallowed directly, and 
hatch in the stomach or intestines. 



Fig - . 50.—The hookworm eggs hatch into little worms which pehetrate 
the human skin, enter a blood vessel, pass to the lungs, enter a 
bronchus, crawl up the windpipe, are swallowed, and thus reach the 
small intestine. 

Soil Pollution Is the Important Thing in the Spread of Hook¬ 
worm Disease. —Unclean wastes from the body are allowed to 
be poured out on the soil. The ground then is not only un¬ 
clean, but is dangerous, because a child walking along bare¬ 
footed is likely to become sick first with ground itch and then 
with hookworm disease. Such children are backward in their 
growth, stunted and weakly. They are not well, and do not 
play and study like healthy children. 

Sewers and Sanitary Outhouses Are Needed. —The best pre¬ 
ventive of soil pollution is a good sewer system, but this 






78 


The Human Body and Its Enemies. 


cannot be had on the average farm. The next best thing is 
well built outhouses. A picture in the back of this book 
shows a poor and a good kind of outhouse. 

No wastes from the human bod}' should ever be allowed to 
be thrown on the ground, as there are too many diseases which 
may spread in this way. People who do not know they have 
any disease may scatter disease germs, for they may be dis¬ 
ease carriers. 

Other Intestinal Worms that cause disease in man are the 
tape worms and round worms. They are spread in a peculiar 
way. The eggs of the tape worm leave the body as in the 
case of hookworm. But these eggs of the tape worm then get 
into the body of the hog or beef or fish, where they hatch into 
young worms. When we eat the flesh of these animals, if it is 
not well cooked, the young worms commence their life in our 
intestines. All meat should be inspected carefully by a meat 
inspector, and it should be well cooked to prevent the spread 
of tape worms, and other diseases. 

Thymol Is the Remedy for Hookworm, but as it is not a 
harmless drug, it should be employed under the advice of a 
physician. No oil of any kind or butter should be taken after 
taking thymol. 

Important Points. 

1. Pellagra is a disease rather new in America, but fairly 
well distributed over the Middle and Southern parts of the 
United States. 

2. We do not know the cause or the nature of the disease. 

3. Pellagra is often curable, and a cold climate seems to 
have a beneficial action. 

4. Hookworm disease is due to the presence in the small 


Pellagra and Hookworm Disease. 


79 


intestines of small worms about half an inch long, which at¬ 
tach themselves to the wall of the intestines and probably 
suck blood. 

5. We know how to prevent and cure hookworm disease: it 
can be prevented by preventing soil pollution from body 
wastes; and it can be cured by small doses of thymol. 

6. The small hookworms, just after they are hatched, can 
pass through the skin and find their way by a complicated route 
to the small intestine, which is their home. 

7. The sanitary outhouse, built according to the directions 
given in the back of this book, will prevent the spread of 
hookworm disease. 

Questions. 


1. Do we know the cause of pellagra? 2. What is the cause of 
hookworm disease? 3. Where do the hookworms live in the body? 
4. What symptoms do they cause? 5. Where do the worms enter the 
body? 6. Describe their journey from the skin of the feet to their 
final home. 7. What is the most effectual way to prevent the 
spread of hookworm disease? 8. Is there a cure for the disease? 9. 
In what kinds of meat are we likely to find tape worms? 



CHAPTER XII. 


Bubonic Plague . 

When the Panama Canal is opened, Texas will be in much 
closer connection than ever before with China, India and the 

Eastern countries generally. 
It is possible that some of 
their cases of bubonic plague 
may stray into our ports, and 
start a focus of the plague in 
our State. We should know 
that the disease is spread by 
rats and squirrels, so that we 
can protect ourselves intelli¬ 
gently. 

Fig - . 46. Ships from foreign countries . 

mig-ht bring - bubonic plague into Plague Affects Animals as 
our seaports. 

Well as Man. —Plague, or bu¬ 
bonic plague, as it is called, is one disease that man shares with 
lower animals. It is due to a germ that lives 
in the lymph nodes, in the lungs and in the 
blood. The disease is a very fatal one. It 
kills a high percentage of men that have it 
and also kills many rats and ground squir¬ 
rels. There is a plague center in California 
at the present time. Only squirrels and rats 
are affected there at present, but now and 

then some hunter catches the disease from Fi f- ! 7- P1 ^ ue , af¬ 
fects squirrels. 

squirrels. 

Plague is also distributed in some of the South American 





Bubonic Plague. 


81 


countries, and some of them are so busy fighting each other 
that they have no time to fight the plague, and hence some 
plague will remain there. 

Plague Is Spread by the Flea. —The interesting thing is that 
it is the squirrel flea that conveys the disease. The huntsman 
kills a squirrel and picks him up. The fleas leave the dead 
squirrel as he gets cold and get on the man and bite him. The 
man develops the disease. 

Rats Are Objectionable. —Rats are dangerous on account of 
other diseases as well as plague, and they are very expensive. It 
is wise to make all premises as nearly ratproof as possible. 
This can be done in the following way: Wooden walks should be 
torn up and replaced by concrete or gravel. The residence 
should be at least eighteen inches up above the ground, meas¬ 
uring from lowest joist. The barn and 
chicken yard should have concrete floors, 
and chicken wire of small mesh (1-2 inch) 
should be used. The woodshed should have 
no floor, and the wood should be piled on 
platforms at least two feet high. Garbage 
should be kept only in iron cans with close 
fitting lid. All grain should be stored in a Fig. 48. Rats spread 
metal ratproof container. 

If the premises are ratproof a little poison will kill off all the 
rats, because there will be nothing ese for the rats to eat but 
the poison. 

In case plague should occur in Texas, quarantine would not 
do much good. The rat and ground squirrel would be the 
point of attack. 



82 


The Human Body and Its Enemies. 


Important Points. 

1. The Panama Canal will bring Texas in close touch with 
the Eastern countries like China and India. 

2. Plague is epidemic in the East, and hence it may enter 
Texas. 

3. Plague is spread principally by the fleas which are 
found on rats and squirrels. 

4. In case plague should break out, we could probably get 
it under control soon, but after it gets a start among the rats 
and squirrels it is a very difficult matter to exterminate it. 

5. The proper way to guard against plague is to extermi¬ 
nate the rat, and if necessary the ground squirrel. 

6. As you will see from Rule 3, Texas Sanitary Code, page 
337, bubonic plague is a contagious disease. 

Questions. 

1. How is bubonic plague spread? 2. What countries are af¬ 
flicted with plague today? 3. In -what State of the United States 
has plague existed and among what animals? 4. How could we 
prevent the spread of plague if it should appear in one of our 
seaports? 


CHAPTER XIII. 


Disease Carriers. 

You have learned that in several ways it is possible for a well 
man to have disease germs in his throat or elsewhere in his 
body. This is particularly true of typhoid fever, diphtheria, 
meningitis, pneumonia and grip. We call these people who 
walk about carrying these dangerous germs, “germ carriers,’’ 
or “disease carriers.” It is hard to believe this kind of thing 
is possible, but we must believe it, for many reliable men, and 
men of good judgment, have investigated, and they say it is 
true. It is easy to prove. 

Typhoid Carriers. —In the case of 
typhoid fever, the carriers are usu¬ 
ally people who have had the disease 
a year or two before. By carefully 
examining all who have had typhoid 
fever, certain scientists have found 
that some healthy men have the ty¬ 
phoid germ in their intestines, or in 
their kidneys. It has been proven to 
be the true typhoid germ. Many peo¬ 
ple have caught typhoid fever from 
these carriers, who were proven to 
have typhoid germs in their bodies. 

Gallstones are often due to typhoid fever. That is, one of 
the after effects of typhoid fever is gallstones, and the gall¬ 
stones may not be noticed for years after the typhoid fever. 
But if people with gallstones are examined they are often 
found to be typhoid carriers. 



Figr. 55.—A typhoid carrier 
handling milk is very 
dang-erous. 






84 


The Human Body and Its Enemies. 


Dr. Robert Koch, the great scientist, who discovered the bac¬ 
terium of tuberculosis, said that if the typhoid carriers could 
be prevented from spreading typhoid fever, the disease could 
be stamped out. The particular danger with typhoid carriers 
is that many of them are cooks, bakers, dairymen and the like. 
One typhoid carrier in New York was a cook and caused 
twenty-six cases of typhoid in seven different families. 


Diphtheria Carriers. —It was a surprise to many doctors when 
it was found that the diphtheria germ could live in the throat 
of a healthy boy or girl without setting up the disease. This 

fact, however, is well proven, too. 
The right way to apply a quarantine 
to a family that has had diphtheria 
is to examine the throats and let 
them go free as soon as their throats 
are found free of the diphtheria 
germ. The same is true of menin¬ 
gitis. 

Meningitis Carriers.— Meningitis is 
such a deadly disease, especially 
when not treated by serum, that it 
seems almost unbelievable that the 
meningitis germ should live in any¬ 
one’s throat without making him sick. But this is most cer¬ 
tainly true. And this explains why people fall sick with men¬ 
ingitis when they have never been near a meningitis patient. 
Without knowing it they have been near a meningitis carrier. 



Figr. 56.—A diphtheria car¬ 
rier. 


Two Lessons. —There are two lessons to learn from these 
germ-carriers: First, we should note how perfectly the human 
body can protect itself against germs, even when the germs 
are actually living in the body; secondly, we should remem¬ 
ber that uncleanly habits are dangerous, even when there is no 


Disease Carriers. 


85 


sickness about, for people who appear healthy may be scatter¬ 
ing deadly germs every day. 


Important Points. 

1. Some disease germs are so harmful that they invariably 
cause disease whenever they live in the human body; the 
germs of leprosy are of this kind. 

2. Other disease germs usually cause disease when they 
live in the body, but some persons are so resistant that the 
germs can live in their bodies without causing disease. 

3. A healthy person who has disease germs living in his 
body is called a disease carrier. 

4. Other people may be killed by the disease germs which 
are harmless to the disease carrier. 

5. Typhoid fever, diphtheria and meningitis are spread by 
carriers. 

6. Persons have been known to carry the typhoid germs for 
years after recovering from the fever. 

7. Typhoid carriers are especially dangerous when they 
work in dairies or other places where food is handled. 

8. It is impossible to tell whether a typhoid convalescent is 
a carrier except by a laboratory examination for the bacteria. 

Questions. 


1. Name three diseases spread by carriers. 2. Can you tell a 
typhoid carrier by his appearance? 3. How do you explain the fact 
that the germs in a disease carrier do not make him sick? (See Chap¬ 
ter IV.) 4. In what occupations are disease carriers most dangerous 
to the public? 5. How can disease carriers be discovered? 6. Sup¬ 
pose you catch typhoid fever from a carrier or from a mild case, is 
your case likely to be mild? 


CHAPTER XIV. 


Insects Which Scatter or Carry Disease . 

The important fact has often been pointed out in these pages, 
for instance in Chapter IX, that disease germs are derived 
from the bodies of persons who are sick. The germs of 
disease are carried from the sick to the well in various 
ways: in the air, in clothing, by insects, by means of drinking 
cups and towels, by contact, in our food and our drinking 
water. In this chapter we shall learn how the house fly 

carries typhoid and oth¬ 
er germs to our food, 
and how blood-sucking 
insects transfer the 
germs of certain dis¬ 
eases from the blood of 
the sick into the blood 
of the well, thereby 
scattering and causing 
disease. Mosquitoes are 
responsible for scatter¬ 
ing yellow fever, mala¬ 
ria, dengue fever and 
several other terrible 
diseases. Ticks spread disease among men, among cattle, and 
among chickens. Whereas formerly it was considered re¬ 
markable that a disease should be conveyed from one person 
to another by insects, we now consider it almost a rule that 
any insect which lives on the blood of any animal is likely to 
convey disease from one of tho^e animals to another. 



Fig. 57.—This picture shows the eggs of 
the fly, and then the larva and pupa 
which the egg changes into before it 
finally becomes a grown fly. The larva 
is called a 



Insects Which Scatter or Carry Disease. 


87 


THE HOUSE OR TYPHOID FLY. 

Description of the House Fly. —The house fly may be called 
one of our domestic animals, for it occurs almost exclusively 
about the habitations of man. Since it cannot bite like its 
“cousin,” the stable fly, it has until recently been considered 
perfectly harmless. It is, moreover, a rather pretty creature, 
with symmetrical body, a pair of gauzy 
wings, compound eyes and agile habits. 

In connection with the fly’s method of 
carrying disease germs, a study of the foot 
and the mouth-parts or proboscis of the fly 
is most important. All parts of the fly’s 
body, especially the feet (Fig. 58), are cov¬ 
ered with stiff hairs well adapted for catch¬ 
ing up filth particles containing disease 
germs. The last joint of each leg of the fly 
carries, first, a pair of claws fitted for hold 
ing on to rough surfaces, and, second, a pair 
of pads between the claws. The pads have 
short, knobbed and sticky hairs, with which the fly is enabled 
to walk on smooth surfaces like a window pane, or upon the 
ceiling. No doubt these acrobatic feats have all seemed won 
derful to you. Would you not suppose that these sticky hairs 
could also take up dust and dirt containing germs of typhoid 
or diphtheria? The proboscis or sucking tube of the fly 
(Fig. 59), is likewise, on account of the presence of numerous 
hairs and bristles, a good collector of filth and disease germs. 

How the House Fly Scatters Disease Germs. —Thus we see 
that we should look upon this otherwise pretty creature with 
fear and disgust. It is really the poisoner of millions of men, 
women and children. The house fly has fitly earned its new 



Fig\ 58.—The foot 
of the fly. 


88 


The Hliman Body and Its Enemies. 


name of '‘typhoid fly.” It revels in filth. It visits the back 
yard of a typhoid patient, where careless people have placed 
the patient’s body wastes. It covers the bristles and sticky 
hairs of its feet with filth and germs, and 
then flies into the kitchen or dining room 
and wipes its feet on bread and meat and 
jelly. “How awful!” you say. Then, be¬ 
ware of the fly! If, perchance, the typhoid¬ 
laden fly drops into a can of milk at a 
dairy, the germs multiply therein and may 
infect dozens of consumers of the milk. The 
fly may carry germs from the body wastes 
of one baby sick with summer complaint to 
the milk bottle with which another baby is 
fed, causing another case of sickness and perhaps death. If a 
consumptive spits upon the sidewalk it is easily possible for 
flies to carry the germs from the sputum or spittle to the candy 
eaten by a boy or girl living next door. The fly frequently car¬ 
ries filth several hundred feet from where he picks it up. Fig. 
60 shows a plate of gelatine over which a fly had been allowed 
to walk. At first no tracks could be seen, for the germs that 
were left by the fly’s feet were too small to be seen. But in 
twenty-four hours each germ had multiplied into a colony of 
thousands of germs. These colonies of germs can be seen in 
the picture. There is no longer any doubt that the fly is guilty 
of the crimes charged against these insects. 

Life History of the Fly. —The fly lays its eggs, as a rule, in 
the filth of horses or of man, the female fly laying about a 
hundred eggs at each brood. The egg hatches in less than a day 
into a legless, wormlike larva or maggot. Each larva feeds upon 
the filth until full grown, when its outer shell turns hard and 



Insects Which Scatter or Carry Disease. 


89 


brown. The insect is then said to be in the pupa, or resting 
stage. While in the shell a wonderful change takes place, 
for soon the shell breaks open at one end and out slips the 
mature or adult fly. It takes about ten days in average 
weather to pass through the 
egg, larval and pupal to the 
adult stage. 

How to Reduce the Num¬ 
ber of Flies.—Flies are plen¬ 
tiful wherever filth or excre¬ 
ment is plentiful. If we re¬ 
move the barnyard manure 
once a week we remove with 
it all of the young flies in 
the larval or egg stage. A 
good plan is to have a box 
or bin (Fig. 61), in which to 
keep the rakings from the 
stable and barnyard. The 
bin should be fly-proof and 
its contents should be 
hauled off once in ten days or oftener. It is much eas¬ 
ier to prevent the hatching of flies than to catch them in the 
adult or winged stage. Fly traps are often useful for catch¬ 
ing the adult flies. There are several good patterns on the 
market. 

Observation Work.—Secure a number of fly traps and place them 
in good situations. Use different bait (moist bread, molasses, sugar- 
water, meat, etc.) in the different traps so as to find out the most 
attractive, bait. It would also be interesting to capture a fly and 
study the parts (eyes, wings, proboscis, feet, feelers, balancers, etc.) 



Fig:. 60.—This shows tracks left by a 
fly in crawling over a flat dish of 
gelatine. Each spot is a colony 
containing millions of germs. 


90 


The Human Body and Its Enemies. 


with a magnifying glass. Disinfect the fly by rolling it around in 
formaldehyde or hydrogen peroxide, and wash the hands in soap 
and water after handling the fly. 


If flies get into the house in spite of all we can do to pre¬ 
vent it, they should be killed. Liquid poisons in sweetened 
water are sometimes used, but they are not to be recom¬ 
mended for the reason that the poisoned flies are likely to 

fall into the food and 
thus do as much 
damage as living 
ones. Sticky fly pa¬ 
per is the best means 
of killing the flies. 
The flail pictured in 
Fig. 62 can be used 
to kill flies as well 
as mosquitoes that 
gather on the inside 
of our screen doors 
and windows. If we 
darken a room, with 
the exception of one window, the flies will gather at this win¬ 
dow, where they may be killed. 

Avoiding Disease. —To prevent the carrying of germs to our 
food we should first try to keep down the number of flies by 
removing their breeding places, and, secondly, screen our 
houses so as to keep the flies out of our kitchens and dining 
rooms. If you doubt the need of screens, take some lime and 
throw it onto the flies out near the stable or closet. Within 
an hour you will probably find flies with lime on their backs 
on your dining-room table. The best screens that can be ob¬ 
tained at reasonable cost are those made of galvanized wire. 



Fig. 61.—A fly proof manure-bin with lid 

























Insects AVhich Scatter or Carry Disease. 


91 


the 

ex- 


To keep out mosquitoes as well as flies the wire gauze should 
have no less than 14 meshes to the inch and 16 would be better. 

But after all the previous precautions advised we still 
have not done the most important thing to prevent 
spreading of the diseases mentioned. If we would not 
expose germ-laden filth to the fly, there would 
be no germs for the fly to carry. The most im¬ 
portant thing to do to prevent the scattering 
of typhoid and other diseases is to disinfect the 
body wastes of the sick, as described in Chap¬ 
ter V. Typhoid fever is a filth disease. Flies 
can only scatter the germs, when the germs are 
placed where the flies can get to them. 

The Tse-tse Fly. —In East Africa there is a 
disease known as the sleeping sickness. This 
is transmitted by the tse-tse fly, an insect 
about the size of our house fly, but different 
in having mouth parts fitted for piercing the 
skin and sucking blood. The germs live in the 
blood of the patient and are sucked up by the fly and then 
injected into the blood of the next person that happens to 
be bitten. 



Fig 


62. — F 1 y 
killer. 


Observation Work.—In the fall of the year horses' are much an¬ 
noyed by big black blood-sucking flies. Capture one, if possible, 
and bring it to school as an example of a blood-sucking insect. 
Squash bugs (found on squash, pumpkins, etc.) might also be 
studied to get an idea of the sucking mouth parts of an insect. In 
this case, however, it is plant juices and not blood that is sucked. 


MOSQUITOES. 

Mosquitoes cause hundreds of deaths in Texas, such deaths 
being due to malarial fever, or what is more commonly known 
as ‘‘chills and fever,” “malaria,” or simply “chills.” In all 
instances it is the mosquito which takes the germ of malarial 




















92 


The Human Body and Its Enemies. 


fever from a person sick with chills and fever and inoculates 
these germs into the blood of a healthy person through its 
bite, thus producing malaria. The germ of malarial fever is 
known as the malarial parasite. 



Dengue fever makes its appearance in this State from time 
to time: and when cases do come in from Mexico and else¬ 
where, mosquitoes are here to spread the disease. Yellow' 
fever threatens to slip in from South 
America every summer, but this will 
probably be prevented by the watch¬ 
fulness of our quarantine officers. 
Yellow fever is not likely to become 
epidemic in Texas again in the pres¬ 
ent advanced state of scientific 
knowledge. The study of the mos¬ 
quito is important mainly from the 
standpoint of preventing malaria 
and dengue fevers. 

Description of a Mosquito. —The 
mosquito is an insect with a single 
pair of wings and a pair of balanc¬ 
ers. For our present purpose the 
most interesting part of the animal 
is the proboscis. This is not a simple 
affair, but a whole set of instruments 
in itself. There are six sharp pointed 
pieces in the proboscis for piercing 
the skin and making the blood flow. 
Then there is a tube, with which to 
suck up the blood, and this tube 
also acts as a duct through which 
the mosquito injects her saliva into the human skin. 


Fig. 63.—Yellow fever mos¬ 
quito (Stegomyia). 



Insects Which Scatter or Carry Disease. 


93 


How the Mosquito Scatters Disease Germs. —The germs of 
malaria are sucked up through the proboscis of the mosquito 
and into its stomach. Here the germs cause knots or cysts in 
the stomach wall and multiply in countless numbers. In four¬ 
teen days the germs are mature, and break out of the mosquito’s 
stomach wall and enter the salivary glands of the mosquito. 
If then the mosquito bites a person, the germs pass into the 
blood with the saliva which the mosquito injects into the wound 
it makes. 


Kinds of Mosquitoes. —Yellow fe¬ 
ver, malaria and dengue are each 
carried by a particular kind of mos¬ 
quito. The accompanying pictures 
show the three kinds, all of which 
occur in Texas. 



Observation Work. —Secure a 
number of mosquitoes and try 
to identify them. This is not 
easy, even after looking at the 


Fib. 65-Malaria mosquito. P ictureS ' The y e,loW feVer m0S ‘ 

quito (Stegomyia) has white mark¬ 


ings in the shape of a 
lyre on the thorax and has 
striped legs. The malarial 
mosquito (Anopheles), when 
at rest, stands at an angle 
from the wall (Fig. 66), and 
has spotted wings; the com¬ 
mon (or Culex) mosquito 
(Fig. 66) holds its body par¬ 
allel to the surface on which 
it rests. 


Fig - . 66.—Showing how the malaria 
mosquito stands out from the wall. 






94 


The Human Body and Its Enemies. 


Breeding Places of the Mosquito. —To destroy these insect en¬ 
emies of ours we must learn their breeding places, and 
the habits of the young stages. We can keep the adult in¬ 
sects out of our houses, but we cannot kill them after they 
have grown wings and flown away. We may, however, easily 
keep down their numbers by filling up or draining their breed¬ 
ing places, and so getting rid of their young. 

Everybody knows that the wiggler of our ponds and puddles 
is the young stage of the mosquito, but not everybody realizes 
what large numbers of mosquitoes may grow up in a very 
small amount of water. A tin can may catch enough rain 
water to raise a thousand mosquitoes in a summer. The rain- 
barrel or the overground cistern is often a source of a continu¬ 
ous stream of mosquitoes throughout the season. Roof gutters 
may become clogged and hold water after every rain. Water 
troughs, hoof prints of cattle in wet ground, urns in cemeteries, 
and even a neglected vase inside the house, may harbor mos- 

The remedy for all this, and the 
easiest way to get rid of mosqui¬ 
toes is to destroy their breeding 
places. City and county authorities 
should see to it that useless accumu¬ 
lations of stagnant water are 
drained. Necessary ponds and tanks 
should be stocked with fish which 
eat the wigglers. Tin cans should 
have holes punched into them and 
should be carried off, and other such 
F ifd. 67 — Rain - barrel with breeding places of the mosquito 

should be removed. The rain-barrel 
and cistern should be made absolutely mosquito-proof with 
screen covers (Fig. 67) and strips tacked over cracks. 















Insects Which Scatter or Carry Disease. 


95 


By referring to Fig. 25 you will see a cistern with the top 
open and exposed to mosquitoes. This cistern could be made 
more sanitary by covering it with boards, or, better yet, boards 
and cloth. 


Life History of the Mosquito. —Before laying a batch of 
eggs the mosquito must gorge herself with food, such as the 

blood of animals or man. She then deposits the eggs on the 

surface of the water, where they swell up and float. The eggs 
of the dengue mosquito, or Culex, are in a raft-like mass of 
200 to 400 (Fig. 68 ) ; those of other mosquitoes are scat¬ 
tered singly on the surface 
(Fig. 69) of the water. The 

eggs hatch in half a day, and 
out come wigglers, or larvae. 
These feed on tiny particles 
of organic material. It is in¬ 
teresting to wtach the brush¬ 
like mouth parts as they rake 
in the food. The Anopheles or 
malarial mosquito larvae lie 
flat upon the surface of the 
water (Fig. 69) ; larvae of 
other kinds feed at various 
levels and float with the head 
downward or submerged. When 
the larva becomes full grown it 
stops eating and becomes a pupa 
(Fig. 68) on the inside of which 
the adult insect develops. When 
the adult is ready to emerge, the 
pupa splits open at the back, and slowly the mosquito comes 
forth, pulling out its legs, feelers and wings, and using the pupal 



Fig. 68.—Showing eggs, larva and 
papa, or the different stages in the 
development of the ordinary or 
dengue mosquito. 



Fig. 69.—Eggs and larva of 
the malaria mosquito. 






96 


The Human Body and Its Enemies. 


skin as a raft until the wings are quite dry. After this it flies 
away to start another generation of mosquitoes. 

How could one witness this magic transformation from worm 
to winged insect without thinking of the butterfly and the 
beautiful Greek story of Psyche, typifying the soul. 

Observation Work.—Every school should organize an anti-mos¬ 
quito brigade. Let the pupils look up and report all of the breeding 
places of mosquitoes in the school ward or school district. 

Observation Work.—It is easy to rear mosquitoes in the school 
room. You may go down to the pond and find eggs, larvae and pupae 
and bring them to school in a glass jar. It is best to use the water 
iri which they are f ound. Study all of the stages. See if the lar¬ 
vae change their skins. Watch the adults emerge. You may also 

set out a jar of rain water where mosquitoes abound and you will 
probably find eggs on the surface of the water in the morning. 

Drop a single cooked bean or bread crumb into the rain water for 

the larvae. If you want to keep some adult mosquitoes in a cage, 
capture a dozen or so, place them in a cage and feed them a slice of 
banana. Let the mosquitoes also have a tumbler of rain water in 
which to lay their eggs. 

Destroying Mosquitoes. —Besides removing the water in 
which the larvae and pupae live, there is another way of kill¬ 
ing them. This method depends upon the way the larvae and 
pupae breathe. In Fig. 68 both are shown at the surface 
of the water, with the breathing tubes protruding in the air. 
If, now, we pour oil on the surface of the water, the oil will 
spread over the surface in a thin film which the wiggler can¬ 
not penetrate. The wiggler, therefore, dies for want of air. 

Experiment.—Place a few wigglers into each of two tumblers of 
water. To one tumbler add one drop of kerosene oil. Keep the 
other tumbler entirely free from oil. Note the result. 

Adult mosquitoes that succeed in getting into our houses 
can be killed with the flail shown in Fig. 62 on the inside of 
our screens, where they gather about dusk. 


Insects Which Scatter or Carry Disease. 


97 


Screens.— Some of the worst yellow fever and malarial dis¬ 
tricts of the world (Havana, Panama,) have been made hab¬ 
itable to man by the fight on the mosquito, by draining pools 
of water, and by the use of screens. Screens are necessary 
in all parts of Texas, both against flies and against mosquitoes. 
The river bottoms of Texas can be made quite safe for white 
people by the use of screens on doors and windows of dwell¬ 
ings. If a person has malaria, he should be carefully screened 
off from the other members of the family, and every precaution 
taken to prevent access of mosquitoes, the carriers of the dis¬ 
ease. 

v 

FLEAS AND OTHER DISEASE CARRIERS. 

Fleas. —Fleas are insects that have lost their wings and de¬ 
veloped their hind legs for hopping. They live on all kinds 
of warm-blooded animals. The kinds 
of fleas that live on rats and ground 
squirrels are the ones most danger¬ 
ous to man, because these animals 
may become infected with plague, 
the germs of which are carried from 
the living or dead rat to man. To T piaVue°' —The flea carries 

fight plague, therefore, we must 

make war on the rat and the ground squirrel, as has been done 
in California in recent years. We have not had plague in 
Texas, but will be in danger of infection from ships coming 
from Asia through the Panama canal. 

Lice. —Body lice transfer typhus or jail fever from the sick 
to the well. This disease occurs in Mexico. Proper sani¬ 
tary measures are almost sure to prevent its introduction into 
Texas. 

Ticks. —Ticks are not strictly insects, but are much like 





98 


The Human Body and Its Enemies. 


them. How many legs has a tick? A spider? An insect? 
Ticks have been proved to carry ‘Hick fever” from cattle 
to cattle. The disease is deadly to imported cattle unless 
they are made immune by a special kind of vaccination, such 
as you studied in chapter TV. Cattle shipped out of Texas 
have to be “dipped” to kill the ticks. 

Another kind of tick is responsible for carrying Rocky 
Mountain spotted fever to people. This disease originated in the 
Bitter Root Valley of Montana, where it causes about a dozen 
deaths annually. It occurs in other States now. 

Summary. 

1. Insects do not originate disease germs, but carry them 
from the sick to the well. 

2. The house fly plays an important part in the transmis 
sion of typhoid fever and other intestinal diseases, carrying 
the germs with filth to the food of man; mosquitoes transport 
germs of malaria, dengue, yellow fever or other diseases in 
blood sucked from the patient; fleas, lice and ticks are also 
known to be carriers of disease. 

8. Flies and mosquitoes are most easily got rid of by de¬ 
stroying their breeding places: barnyard filth for flies and 
stagnant water for mosquitoes. Rakings from the barnyard 
should be stored in a bin provided with a lid. Necessary 
standing water should be oiled and barrels and cisterns thor¬ 
oughly screened. 

4. All dwellings should be provided with fine wire gauze 
screens especially to keep out the typhoid fly and the ma¬ 
laria mosquito. Food at stores and restaurants should also be 
protected from flies. 


Insects Which Scatter or Carry Disease. 


99 


Questions. 

1. Name the insects that scatter disease and tell what disease each 
kind scatters. 2. How is the house fly adapted to gathering germs? 
3. What is another name for this insect? 4. How can we best kill 
the adult fly? 5. Describe the development of the fly. 6. How can 
we prevent flies from multiplying? 7. How often should the barn¬ 
yard bin be emptied, and why? 8. Describe the development of the 
mosquito. 9. How can we prevent mosquitoes from multiplying? 
10. How do wigglers breathe? 11. How can we kill them? 12. How 
can you tell a larva of a malarial mosquito from other kinds? 13. 
How can you tell the adults apart? 14. Point out the eggs, larva 
and adult of the malarial mosquito in the pictures; also the adult 
in resting position. 15. How can we kill the adult mosquito? 16. 
Why is it more necessary to screen a patient sick with malaria 
than one sick with typhoid fever? 17. State three reasons why 
we should screen our houses. 18. How is plague spread? Typhus 
fever? Tick fever of cattle? 19. What would we have to do if 
plague should break out in Texas? 20. Which of the diseases men¬ 
tioned above is it now most important for us to study about in 
Texas? 


v » 
» • O 




CHAPTER XV. 

Keeping Germs Out of Our Drinking Water. 

What are the things about drinking water that make it un¬ 
safe? This question is easy to answer; it is not the mineral 
matter, nor the decaying matter which a water may contain, 

but it is the germs of disease 
that harm us. Of course, 
there are poisonous waters 
that are not useful as drink¬ 
ing water, such as the strong 
gypsum waters found in cer¬ 
tain parts of Texas; and 
there are some stagnant 
pools that are so full of filth 
that they would not serve 
as drinking water; but, on 
the whole, the only dangers 
that lurk in drinking waters are in the form of disease germs, 
and in this country, typhoid germs are the most to be feared. 

Water May Be Clear and Palatable and Yet Be Impure.— 

Disease germs are not visible except when placed under a mi¬ 
croscope or viewed in large numbers, and it is impossible to 
tell by looking at a water or tasting it whether it is free from 
dangerous germs or not. There are many wells and springs 
which furnish water of a pleasant taste; such water may seem 
to be perfectly clear; and yet this water may contain hun¬ 
dreds of typhoid germs in each drop. It is important to real¬ 
ize how impossible it is to judge a specimen of water by its 



Fig:. 71.—Boy drinking: from artesian 
well. 


Keeping Germs Out of Our Drinking Water. 


101 


appearance and taste. A much better way to form an opinion 
as to the purity of water is to examine into the source of 
the water. 

Kinds of Water Used in Texas. —In general there are five 
kinds of drinking water used in Texas, as follows: rainwater, 
shallow well water, spring water, river water, and deep 
well water. 

Rainwater is per 

fectly pure when it 
falls, but when it 
falls on a roof that 
has been soiled by 
English sparr o w s 
and pigeons, it may 
become pois o n o u s 
from the disease 
germs it contains. 
Underground c i s - 
terns subject to over¬ 
flow or seepage may 
contain germs of ty¬ 
phoid fever. Water 
should be gathered in 
a cistern only from the sunny side of the roof, as sunlight 
is a good killer of germs. The gutters should be cleaned as 
often as necessary. Only water from winter rains should be 
allowed to flow into the cistern. Cisterns are of great im¬ 
portance as the breeding place for mosquitoes, as you have 
learned in Chapter IX. 

The shallow well is the source of most of the drinking water 
used in many parts of Texas. This kind of well is usually less 
than a hundred feet deep, and includes practically all wells 



Fig:. 72.—Showing: how cistern water is made 
impure by birds, which carry filth from the 
ground to the roof. 









102 


The Human Body and Its Enemies. 


except the deep or artesian wells. The shallow well is one of 
the most dangerous sources of water, but it can be made 
reasonably safe in most instances. In nine cases out of ten, 
the fault lies not in the lay of the land, but in the way the 
well is cased in, the method of drawing the water, or other 
things which can be corrected. When we take into account 
the fact that usually the water in a shallow well has filtered 
or seeped through at least twenty feet of closely packed earth, 
we must conclude that most of the germs would be filtered 
out. It is certainly true, however, that if a well is located 
close to a cesspool, especially on the down-hill side, and if 
this cesspool is filled with unclean material month after month, 
sooner or later, some disease germs are going to pass entirely 
through the soil and into the well. It is rare, however, that 
a well is located in such a foolish position. We may, there¬ 
fore, conclude that the germs which filter or seep into a well 
from the bottom with the water are not so important as the 
germs that spill in over the top of the well or those that 
trickle in through leaks in the side of the well. Not only 
should the well be cased in, but the platform or cover of the 
well should be watertight in order to prevent the well from 
being soiled with material dropping off the shoes of the per¬ 
sons drawing water. 

Wells Should Be Properly Cased in.—Fig. 73a. shows a typi¬ 
cal faulty shallow well. Point out four errors in the con¬ 
struction of this well. Fig. 73b. shows the same well with the 
faults corrected. Ordinarily it costs about fifty cents a foot 
to dig a well in Texas. The model well shown in the picture 
•is cased from bottom to top with concrete rings, which are 
fitted together with cement so as to make a perfectly water¬ 
tight joint. These rings are usually molded to fit a standard 
well, three feet in diameter, and it takes about thirty dollars 


Keeping Germs Opt of Our Drinking Water. 


103 


to pay for the casing in of a well thirty feet deep. The con¬ 
crete rings are superior to brick or stone because they have 
fewer joints. The model well shows the concrete rings built 
up two feet or so above the surface of the ground, and when 
this is done, the mound around the surface of the well is un¬ 
necessary. It is a good rule, however, to hill up the soil 



Fig 73a.—An improperly con- Fig. 73b.—A good well. Less chance 

structed well. for entrance of germs. 

around the top of every well to prevent surface water from 
running in. To make a still better well, a two-inch cap of 
concrete can be placed over the mound for a distance of 
three feet from the well in every direction. This is pic¬ 
tured also. 





























104 


The Human Body and Its Enemies. 


Rope and Bucket Are Not so Sanitary as a Pump. —The 

model well is fitted with a pump. This delivers the water into 
the bucket in a pure state. If the water is drawn with a rope 
and bucket, the drippings from the hands are almost sure to 
fall into the bucket. From what you have learned about ty¬ 
phoid fever you can readily see how easy it would be for a 
person nursing a case of typhoid fever to transfer the germs 
from her hands to the water. 

Spring water is not a safe water supply if we take it year in 
and year out. It gets its supply of water from the surface 
also. The spring is not usually dangerous, however, if it be 
protected so that no water can get in except through the 
fountain head of the spring. A spring should have a con¬ 
crete curb around it to keep the nearby surface from drain¬ 
ing into the spring. If a spring is on the down hill side of 
a house, and most of them are down hill, and if a house is 
close by, it is dangerous, especially if it has not a watertight 
curb or rim around it. 

River water is the main source for the water of most of our 
cities, and is usually so dangerous that it has to be treated 
in some way before it is safe to use at all. It is easy to see 
that many filthy things get into a river, and were it not for 
the purifying action of the sunlight and air, and the filtering 
of the sand, river water would be entirely unusable. River 
water is especially dangerous when a city or town is up¬ 
stream; in other words, river water is especially dangerous 
just below a city or town. Some cities keep an account of all 
cases of typhoid that occur along the banks of the river for 
miles and miles above their intake pipe. 

At this time there is some danger from the water supply 
of several of the cities of Texas, and a good plan would be, 
in case of an epidemic of typhoid in any city or town, to 


Keeping Germs Out of Our Drinking Water. 


105 


ask your local health officer about the water supply. In 
case of doubt, boil the water. Do not forget the fly and the 
milk supply, however. 

Deep well water is absolutely safe, provided no surface 
water can leak in from the 
top. If the casing is water¬ 
tight no leakage can occur. 

The casing is usually made 
of iron pipe. 

Importance of Water Sup¬ 
ply of Summer Camps. —The 

pleasant climate of Texas, 
and the excellent facilities 
for enjoying camp life entice 
many campers out into the 
groves and prairies each 
year. It is not at all uncom¬ 
mon for these campers to contract typhoid fever while out on 
their vacation, and as the fever requires two weeks to de¬ 
velop, these spells of fever usually come on after the campers 
have returned to the town or city. We should learn from 
this the necessity for being careful about selecting drinking 
water even when out for a few days’ trip. The picture shows 
a lad drinking from a little brook. These little streams are 
often poisoned by the germs which have washed into them 
from the premises of farmers up the stream. 

Contamination May Occur After Water Is Drawn. —Even if 
we have a good water supply, bacteria may get into the water 
after it is drawn unless we take certain precautions in the 
handling of it. The public drinking cup is a great danger. 
You have learned in Chapter III and others how the secre- 



Fig. 74.—Boys out hunting should not 
drink from little streams. 





106 


The Human Body and Its Enemies. 


tions from our bodies are likely to contain the bacteria which 
cause disease. Each time that we put a drinking cup to our 
lips, some of the saliva which has dried on our lips is removed 


B 




A 

PIEC& 

OF 

PAPER 
7 INCHES 


' FOLD 

Aon toB 
ALONC* LINE 

D C 





FOLD B &ALK, 
OPEN ALONCx 
^ THE LINE £ £ 

A (VO Y QU HftU£ A 

- SANITARY - 
DRlNKkNG CUP. 



Fig. 75.—This picture shows how to make a sanitary drinking cup. 


by the cup. Needless to say, any germs that are in our system 
are likely to be spread in this way. It has been proven that 
the germs of diphtheria, tuberculosis, typhoid fever and other 
dangerous diseases have been distributed by the public drink¬ 
ing cup. (See Sanitary Code, p. 337, Rule 61.) 

How to make a sanitary drinking cup out of a square sheet 



























Keeping Germs Out of Our Drinking Water. 107 

of paper is shown in Fig. 75. In making these cups be sure 
to start out with a clean sheet of paper, and do not put the 
fingers inside to pull it open. The sanitary cup should be 
made by the person who is going to use it, and should be 
used only once. 

The Sanitary Drinking Fountain.— In public places the san¬ 
itary fountain is coming to be used. One of these is shown in 
Fig. 76. They should be 
made with the valve out of 
reach of the fountain, so that 
they must be turned on be 
fore one begins to drink, and 
continue to run till after he 
stops drinking. If they are 
made with the valve close to 
the fountain, some children 
place their mouths on the 
outlet before turning the wa¬ 
ter on. This defeats the ob¬ 
ject of the sanitary fountain. 

Typhoid fever is without 

iii Fig-. " 6 -—Sanitary fountain in one 
doubt the disease we should Of the Houston schools. 

think of when we study the 

water supply. We should not, however, forget that the fly 
probably causes more typhoid fever in Texas than the drink¬ 
ing water. You have learned in Chapter V how to tell 
whether a given epidemic is due to drinking water. In towns, 
if the epidemic is due to water, it is likely that a great many 
persons will be affected at the same time, and all parts of 
town using a given water will be equally affected. If the 
epidemic comes up in spring time, and gets gradually worse 
as the summer wears on, and as the flies increase, it is not 





108 


The Human Body and Its Enemies. 


likely to be due to the water. It is more likely to be due to 
the fly, especially if certain unsanitary parts of town are 
affected worse than others. 

Cholera is spread by drinking water also, but that disease 
is not likely to attack us. It has been almost stamped out in 
the greater part of the civilized world. Hookworm disease 
may be spread by drinking water to some extent, and it is 
probably widespread in the older parts of the State, espec¬ 
ially in the sandy regions. Amebic dysentery is spread by 
drinking water, but there is not a great deal of it in Texas. 
It is likely to be brought in at any time from Mexico, but i3 
not an epidemic disease. 

All Typhoid Germs Come From the Bodies of the Sick.— 

Probably the most important thing 
to remember in connection with the 
spread of disease by drinking water 
is the fact that the germs have to 
originate in the body of some one 
sick with typhoid or other disease. 

If the germs are not poured out on 
the ground, they cannot be washed 
into the well or river. We see at 
once that the best place to attack 
disease is in the sick room, and the 
best method of attacking it is to 
disinfect all body wastes so that the 
germs are done away with forever, 
to disinfect in Chapter V, and will learn more about it in 
Chapter XVI, which is devoted entirely to disinfection. When 
we disinfect the body wastes we are “heading the germs off” 
from our drinking water. 



Fig:. 77.—“Heading: the germs 
off” from our drinking 
water. 


You have learned how 



Keeping Germs Out of Our Drinking Water. 


109 


Important Points. 

1. It is not the chemical or mineral contents of water, but 
the bacteria, which make it unsafe. 

2. A water may be clear and palatable and yet dangerous. 

3. Cistern water may be contaminated by bacteria carried 
to the roof by pigeons and sparrows, or it may be contam¬ 
inated by surface water which overflows or leaks into the 
underground cistern; owing, however, to the mosquitoes which 
breed in cisterns, they are usually of more importance in the 
spread of malaria than of typhoid. 

4. The shallow well is dangerous, but can be made a reas¬ 
onably safe source of drinking water by observing the loca¬ 
tion of the well, by casing it in properly, by covering the 
well properly, and by having a pump to raise the water. 

5. River water is risky and usually has to be treated by 
filtration when used as a public water supply; in time of an 
epidemic in towns and cities the water should be boiled till the 
cause of the epidemic has been found and removed. 

6. The deep well, when properly cased in, supplies a per¬ 
fectly pure water. 

7. Bacteria are frequently introduced into drinking water 
after it leaves the well, as, for instance, by the public drink¬ 
ing cup. 

8. Typhoid fever is the disease which drinking water 
spreads, although this disease is spread in other ways also. 


110 


The Human Body and Its Enemies. 


Questions. 

1. Why must we be careful in selecting drinking water? 2. Of 
all diseases spread in Texas by drinking water, which one causes 
the most deaths. 3. Do you understand this to mean that water is 
the only cause, or most important cause of the spread of this dis¬ 
ease? 4. What are the dangers of the uncovered cistern? 5. What 
is the object of locating a well on the uphill side of a house? 6. 

What is the object of casing the well in, and how should it be 

cased in? 7. Why is a pump safer than a bucket and rope? 8. 

What is the object of having a watertight platform or cover for 

the -well? 9. Why should the earth be hilled up around the 
well? 10. What disease can be spread by the public drinking cup? 
11. What is the danger in placing one’s mouth over the outlet of a 
sanitary fountain before the water begins to flow? 12. Fold a sani¬ 
tary drinking cup. 13. Where do the disease germs come from that 
are in drinking water? 14. Where is the best place to kill these 
germs? 


CHAPTER XYI. 


Disinfection, or How to Kill Bacteria. 


In this chapter we shall learn how to kill bacteria in various 
ways. They are very easy to kill if one knows how, but they 
are not all alike, and what will kill one variety of bacterium 
may not kill another. So the question is an important one to 
study. Remedies that kill germs are called germicides, disin¬ 
fectants, or antiseptics. 

Sunlight and Fresh Air Are the Best Disinfectants : They kill 
germs better than any other remedies, and they are also very 
helpful to human beings. So wher¬ 
ever we can get a supply of bright 
sunlight we shall not have man.v 
germs. There are some things, how¬ 
ever, that we need to notice about 
the action of the sun on bacteria; 
for instance, the sun must shine di- 
directly on and against the body of 
the bacterium before it can kill it. 

If you take some tuberculosis germs 
and place them in a thin layer on a 
pane of glass, and then put this in 
the sunlight, the germs will be dead in a few hours. But if 
you take the germs and throw them on the ground, some of 
them will remain on the top of the ground and can be readily 
reached and killed by the sunlight, while others may sift down 
into the dirt so that the sun cannot shine upon them. These will 
not be killed until the sun lias shone on them for many hours. 



Fig-. 78a. Sunlight is a good 
disinfectant. 


112 


The Human Body and Its Enemies. 


Inside the house in dark corners the germs of tuberculosis can 
live for months. 

Next to the sunshine, soap and water are the best disinfect¬ 
ants for everyday use. If we use plenty of water and plenty 
of good soap, our skins will be kept 
almost free of germs. If we keep 
the hands clean we shall escape 
those diseases spread by fingers, 
such as typhoid fever. 

Difficulties of Disinfection. —But 
there are times when we wish to 
destroy all germs in a certain place, 
and do it at once. In these cases we 
can use heat, or we can use certain 
powerful chemicals or drugs. You 

will see that we are now dealing Fig. 78b. soap and water: 

... another good disinfectant. 

with disinfectants powerful enough 

to kill any germ, or to kill even human beings, if they are 
not used properly. And we might as well learn here that 
germs are to a certain extent like human beings, because they 
are living things; and that whatever tends to kill the germ, 
might also tend to kill the human being. This will make clear 
to you the difficulty of killing germs when they are in our 
bodies. You see, we must try to find something that will kill 
the germ without injuring our bodies. We have found a few 
remedies of this kind, and one of them is quinine. Quinine is 
very poisonous to the malarial germ, and, when taken in the 
proper dose, will almost always kill all that are in the patient’s 
blood. At the same time quinine is not injurious to the aver¬ 
age man. But quinine is not very poisonous to germs other 
than the malarial germ. 

Unfortunately, we have no chemical that will kill the tuber- 



Disinfection, or How to Kill Bacteria. 


113 


eulosis germ in the human body without injuring the body itself. 
For this reason, all cures of consumption are frauds, and no 
man who is honest Avill claim to be able to give medicine that 
will rid the human system of the bacteria of tuberculosis. 

Boiling Kills Germs. —But in case the bacteria which we wish 
to kill are not in the human body, our task is much easier. Ten 
minutes’ boiling will kill any bacterium known. One minute’s 
boiling will kill almost all bacteria. But there is a special trick 
by which certain bacteria can withstand boiling for several min¬ 
utes. They have a way of forming a hard shell around them¬ 
selves, and when they have done this 
they are safely shut up like a turtle 
in his shell. It is only certain kinds 
of bacteria that form these shells, 
and we call the bacterium with its 
shell around the outside a “spore.” 

The tetanus or lockjaw germ, and 
the germ of charbon, which attacks 
cattle, are two germs which have 
the habit of forming spores. You 
will see that our worst diseases, such 

as tuberculosis and typhoid fever. Fig:. 79a. Boiling' water is an 
. excellent disinfectant. 

are caused by germs that are very 

easy to kill, once we get at them. The meningitis germ is very 
easy to kill. One minute’s boiling will kill the germs of most 
diseases. 

Chemical Disinfectants. —But it is not always convenient to 
boil things, and there are certain chemical disinfectants which 
will kill germs just as certainly as heat. Probably carbolic acid 
is the commonest one of these. A solution of carbolic acid, 
made by adding one tablespoonful of the acid to a quart of 
water, will kill any of the germs except the spores in five min- 




114 


The Human Body and Its Enemies. 


utes. Now, this is a strong solution, and yet it takes five long 
minutes to kill the germs. Some people have the mistaken 
idea that a saucer of carbolic acid placed under the bed will 
disinfect the entire room. 

There is a mistaken idea in the minds of some people who 
believe that by removing bad odors they can disinfect a room. 
Some even go so far as to believe it is sufficient to cover up 
these bad odors with other stronger ones. This is not only 
useless but is harmful, because it gives a sense of false security 
or safety. In the toilet rooms of many public buildings, hotels 
and the like, are to be found little metal cylinders which give 
off a peculiar odor. These are not of any service in destroying 
disease germs. It would be just as sensible for us to use per¬ 
fume instead of bathing as it is to place these strong-smelling 
cylinders in our buildings. Another mistake made by some 
people is that of confusing disinfectants with insecticides. 
There are some remedies which are sure death to insects but 
harmless to germs; there are also some remedies which kill 
germs effectively but do not harm insects. The gasoline mix¬ 
tures which do such good service as insecticides are usually in¬ 
effective as disinfectants. 

The following table shows how the various disinfectants 
should be diluted for use, and tells which are most dependable. 
All things considered, the coal tar disinfectants are the most 
effective and the cheapest disinfectants. There are several of 
these preparations on the market, and the State Bacteriologist 
has prepared a list giving the exact strength of each disin¬ 
fectant. This list will be furnished upon request to the State 
Board of Health at Austin: 

In buying: a disinfectant always take into consideration how much di¬ 
luting is required. It is best to rely upon reports made by the Marine 
Hospital service at Washing-ton or the State Board of Health at Austin, 
as to the strength of a given disinfectant. Of two disinfectants at the 
same price, buy the one of greater strength, which will require greater 
dilution and “go farther.” 


Disinfection, or How to Kill Bacteria. 


115 


Table Showing How Long It Takes Certain Disinfectants of Given 
Strength to Destroy Germs. 

Name of Disin¬ 
fectant. 

Name of 
Germ. 

How to Make 
Solution. 

Length of Time 
Needed to De¬ 
stroy Germs 
Mentioned. 

Boric Acid. 

Typhoid. 

Tea spoonful to 
teacup of water 

Does not destroy 
all of the germs 
even in a week’s 
time. 

Boric Acid. 

Pus Germs. 

All that will dis¬ 
solve in water 

Has very little 
effect on germs 

Carbolic Acid. 

Typhoid. 

Tablespoonful to 
quart of water. 

Five minutes. 

Carbolic Acid. 

Pus Germs. 

Tablespoonful to 
quart of water. 

Five minutes. 

Carbolic Acid. 

Charbon Spores. 

Two tablespoon¬ 
fuls to pint of 
water. 

Spores live four 
to fort y - fi v e 
minutes. 

Corrosive Subli¬ 
mate. 

Typhoid. 

Three grains to 
pint of water. 

Five minutes. 

t 

Corrosive Subli¬ 
mate. 

Pus Germs. 

Seven grains to 
pint of water. 

Five minutes. 

Corrosive Subli¬ 
mate. 

Charbon Spores. 

Three grains to 
pint of water. 

Twenty-six hours 

Coal Tar Disin¬ 
fectants. 

Typhoid. 

T e aspoonful to 
pint of water. 

From one-half to 
five minutes. 


Fumigation.—So far, the chemical disinfectants mentioned 
are useful only where we can place the thing to be disinfected 
into the solution. But when we come to disinfect an entire 
room, as, for instance, when we move into a rent house, we 
cannot do this, and so we have to use a gaseous disinfectant, 
such as formaldehyde. The formaldehyde method of disin¬ 
fecting a room is very effective, is not difficult, and does not 
damage any of the furnishings usually found in a living room. 
The following directions are taken from the book of instruc¬ 
tions of the Texas State Board of Health: 













116 


The Human Body and Its Enemies. 


To fumigate an average sized room the only utensils needed 
are an old three-gallon scrub bucket made of zinc (not wood) 
and three bricks. Secure from the drug store 13 1-2 ounces of 
potassium permanganate and a quart of formaldehyde. Place 



Fig. 79b. Fumigating a room in a rent house. This should always be done 
except in a house that is new, or one in which the family moving out 
were in perfect health. Books are shown in these pictures, but are not 
well disinfected by this method. They should be burned if infected 
by dangerous disease germs. 

the bricks in the center of the room on the carpet or the floor 
and the bucket on the bricks. Close the room up tight and 
place strips of wet paper over all cracks and openings. Put the 
permanganate into the bucket and pour the formaldehyde over 
it. Leave the room at once, closing the door tightly, and do 
not open the room for at least six hours. It is a good plan 
to stretch all linen, quilts, etc., on a line so as to expose as much 

















































Disinfection, or How to Kill Bacteria. 


117 


surface as possible to the disinfectant gas. They should not be 
thrown ; n a heap. (See also Sanitary Code for Texas, page 
337, Rules 55-60.) 

Mixed Disinfectants Are Not Good. —Just here we might no¬ 
tice the effect of mixing disinfectants. If we take half the 
proper amount of carbolic acid to kill typhoid fever germs in 
five minutes, using one-half tablespoonful instead of a whole 
spoonful to the quart of water; and if we add to this half the 
proper amount of corrosive sublimate to kill typhoid germs in 
five minutes, using one and one-half instead of three grains to 
the pint of water, we will then have a solution which ought to 
kill typhoid germs in five minutes; for there is half enough 
carbolic acid to kill them, and there is half enough corrosive 
sublimate to kill them. But the two chemicals do not reinforce 
each other very much, and the mixture will not kill the germs 
in five minutes. This would teach us not to mix disinfectants. 
For this reason all the patented mixtures sold as antiseptic 
are not so good as solution of carbolic acid for disinfecting. 
For this reason also the small sulphur and formaldehyde can¬ 
dles, which are often sold are worthless. 

Important Points. 

1. The soap and water and sunshine will have a great influ¬ 
ence on your daily life. Keeping your hands clean, and cleans¬ 
ing them especially before eating, will be a health-saving habit 
for you to form. 

2. The knowledge of the chemical disinfectants will be use¬ 
ful to you principally in teaching you the worthlessness of 
most so-called antiseptic treatments. You have learned that 
it takes strong chemicals and a considerable length of time 
to kill bacteria. 


118 


The Human Body and Its Enemies. 


3. Every family should fumigate or disinfect each house 
before moving into it, unless they know something of the his¬ 
tory of the house and its occupants for the twelve months 
preceding their occupancy. 

Questions. 

1. Name ways of killing germs. 2. Is it easy to kill germs in the 
human body? 3. How long can disease germs live in boiling water? 
4. What are spores? 5. Name one disease germ that forms spores. 
6. What two things are of importance in killing germs with carbolic 
acid in water? 7. When should we disinfect a room by fumigation? 


CHAPTER XVII. 


The Most Valuable Thing in the World. 


What is the most valuable thing on earth? Some of you 
may answer friendship, gold, radium, platinum, diamonds. 

There is one 
thing, li o w- 
e v e r, which 
we must have 
before we can 
use or enjoy 
any of these 
things, and 
that is life it¬ 
self ; the most 
valuable 
thing in the 
world then is 
human life. 
Bookkeeping 
—Every mer¬ 
chant keeps a set of books showing the money he takes in 
and pays out. He does this because the money is worth a great 
deal. Just so, every civilized government keeps a set of books 
dealing with lives, as well as dollars. This set of books shows 
the number of lives received each day, or, in other words, the 
number of little babies born. It shows also the number of 
lives paid out each day, and what they were paid out for; 
that is, the number of deaths and what the deaths were caused 
by. If a merchant finds that he is paying out a great deal of 
money for coal, he will try to find some way to stop the ex- 


Iff 

911 — VITAL 


STATISTICS 


Tuberculosis 

3137 


Pneumonia 

1756 


Typhoict 

m 


DeninoiTis 

a, 57 


Ma/a-ria 

3Y9 


G*ip 

1 33 


DipbThfRiA 

Ztl 

i 

Ulfioopiu^ cough 

IZO 


N£asIe.s 

ZXi. 

| 

Tetanus 

U 


ScarJeTFlve.* 

toS 


SmaI|j>ox 

**7 






_ 


Fig. 80.—These figures show the deaths from certain 
preventable diseases in Texas during 1911. 




















120 


The Human Body and Its Enemies. 


pense, beause money is valuable to him. Just so, if the gov¬ 
ernment finds it is paying out a great many lives each day 
on account of typhoid fever, for example, the government 
will try to stop the disease, because the lives are valuable. 
Now, this set of books kept by the government we call “Vital 
Statistics. ’ ’ 

Usefulness of Vital Statistics. —There is no use in keeping this 
list of deaths unless it is studied with a view of saving life. 
And, on the other hand, it is hard to try to save people from 
sickness unless you have a list showing which diseases are 
killing the most people. Suppose the pupils in your school 
wished to try to help prevent disease, and started in by study¬ 
ing the plague. There hasn’t been a case of plague in Texas, 
however, for many years; probably there has never been any 
here. You could not help Texas people much in that direc¬ 
tion, could you? But by observing the records of vital sta¬ 
tistics you will see that typhoid fever kills a hundred people 
or more in Texas each month; you might then do some good by 
trying to prevent typhoid fever. After you had been at w r ork 
a year or two and found that typhoid was killing only fifty 
people in a month, you would feel that you were going at the 
business of life-saving in the right way, wouldn’t you? It 
would be foolish to try to prevent disease without keeping a 
complete record, so as to see where prevention was needed, and 
to see whether prevention was a success. 

Other Purposes of Vital Statistics. —It has been found that 
vital statistics can be made to serve other good purposes be¬ 
sides protecting the public health. The official records of 
births and deaths, for instance, are useful in settling disputes 
as to age and inheritance. Most States that have a system of 
vital statistics require a death certificate to be signed and 
filed with the proper officer before allowing a burial to take 


The Most Valuable Thing in the World. 


121 


place. Murderers and poisoners find it impossible to get a 
death certificate signed, because there is no physician who 
knows the cause of death, and hence the body of the victim of 
the crime cannot be buried legally. When the murderer tries 
to get a physician to sign the certificate, or tries secretly to 
bury the body of the victim, he is frequently detected and 
brought to justice. 

Undertaker Fills Out Death Report, But Physician Must 
Specify Cause of Death. —It has been found most practical to 
require the undertaker to fill out and prepare the death cer¬ 
tificate, for oftentimes the physician rarely goes back to the 
house after the patient’s death. The undertaker always has deal¬ 
ings with the family just after the death occurs, and hence 
he is best situated to get the information required on the 
death certificate. The physician, however, is the only person 
qualified to pass on the question of the cause of death, and 
so the law in Texas requires him to sign the death certificate, 
giving the cause of death. The report of the death is filed with 
the city physician in case the death occurs in a town or city; 
if it occurs in the country, or outside of an incorporated 
town, the report of the death is sent by the un¬ 
dertaker to the county clerk. The officer who first receives 
the death report sends it to the State Registrar of Vital Sta¬ 
tistics at Austin, and once each month the State Registrar 
publishes a statement of the causes of all deaths reported 
during the month. (Study in this connection the Sanitary 
Code for Texas, page 337, Rules 34-50.) 

Texas Statistics Are Valuable But Incomplete. —Up to this 
time a little more than half of the United States preserves com¬ 
plete and accurate vital statistics. In the thinly settled parts 
of the country it is hard to get the deaths and births reported. 


122 


The Human Body and Its Enemies. 


Texas lias not succeeded yet in getting complete reports of 
all its deaths, but it has been making rapid improvements in 
this regard, and no doubt will have a complete set of re¬ 
turns before a great while. We cannot compare our Texas 
vital statistics with those of other parts of the United States 
without making certain changes to make up for the incom¬ 
pleteness of our reports. But we can make these changes, 
and in that way, with a fair degree of accuracy, compare our 
health conditions with the conditions in other States. 

Comparison of Texas With Other States.—We will begin 
by assuming that Texas has about the same annual death rate 
as Indiana, or 13.5 per thousand. In order to make comparison 
easy, it is customary for all death rates to be calculated on 
a basis of so many per thousand inhabitants, or so many per 
hundred thousand inhabitants. When this is done it saves us 
the trouble of taking into account the number of inhabitants 
of each place. The following table shows the death rates of 
several States from several of the important diseases. The 
figures from the United States as a whole are given in order 
to give us an idea of the average death rate over the entire 
country. The rates from Massachusetts are given because 
this is an old and thickly settled State, and has an especially 
good set of health - laws. The rate from Indiana is given 
because this State is largely agricultural, like Texas, and 
hence the conditions in the two States are more or less 
similar. 

In the table the first column of figures refers to the annual 
death rate per thousand of population; all the other col¬ 
umns refer to the annual death rates per hundred thousand 
of population: 


The Most Valuable Thing in the World. 


123 



All 

Typhoid 


Causes. 

Fever. 

United States. 

. .15 

23.5 

Massachusetts . 

. . .16.1 

12.4 

Indiana . 

..13.5 

34. 

Texas . 

...13.5 

48.3 

Paris, France., 

.. .16.7 

7.0 


Tuber¬ 

Measles. Scarlet 

Sm’11- 

culosis. 


Fever 

pox. 

139.7 

12.3 

11.6 

0.4 

137.6 

11.6 

8.0 

0.0 

144.9 

16.6 

7.5 

0.1 

136.1 

4.6 

1.9 

2.0 


From this table we learn that Texas makes a favorable show¬ 
ing so far as the more contagious diseases are concerned, but 
makes a very poor showing in the case of typhoid fever, in 
proportion to her population Texas loses almost four times as 
many citizens from typhoid fever as Massachusetts, over twice 
as many as the United States as a whole, and over eight times 
as many as Paris, France. 

Important Points. 

1. A good system of vital statistics is necessary as the 
first step toward intelligently attempting to improve the pub¬ 
lic health. 

2. Our Texas system is not perfect but is very valuable, 
and we should make every effort to improve it. 

3. It can easily be seen that we have in Texas more than 
our share of typhoid fever. 

Questions. 

1. What are vital statistics? 2. Why do we keep accounts of 
births and deaths? 3. Have we valuable statistics of deaths in 
Texas? 4. Are they perfect? 5. Who should report deaths? 6 
Whom should he report them to? 7. Compare the death rate from 
typhoid fever in Texas with that in Massachusetts. 8. Compare 
the death rate from measles in Texas with that in Massachusetts or 
Indiana. 





CHAPTER XVIII. 


The Body a House of Many Parts. 


Up to this time you have learned 
of the microscopic bacteria which 
sometimes invade the body in count¬ 
less swarms, and which tend to de¬ 
stroy our health by the poisons they 
give off into the blood. Truly won¬ 
derful it is how our bodies can de¬ 
fend themselves against their ene¬ 
mies, the germs of disease, as has 
been described in the preceding 
pages. We shall now learn many 
other wonderful things that the va¬ 
rious organs of the human body have 
to do. We shall study the physiol¬ 
ogy of the organs, that is, their func¬ 
tions or duties, and how they per¬ 
form these. To understand their 
functions we must first learn the 
structure of the organs; this study is 
called Anatomy. After you have 
learned the function and the struc¬ 
ture of an organ or system of organs, 
you will be told how to keep the organs in a condition favor¬ 
able for doing their duty properly. The last study is called 
Hygiene, or the “Science of Health.” 



small 

inTESTIMt 


Fig - . 80a.—Diagram of a 
section through the body 
to show the location of 
the principal organs 


Review and Observation Work.—Review Chapter I; draw an out¬ 
line sketch of Fig. 80a, and in drawing name the organs men- 





The Body a House of Many Parts. 


125 


tioned in the chapter. If possible, secure a manikin or model of the 
human body, and, with the aid of this, study the organs. 

Organs. —From the frequent use of 
the word organ, and from your study of 
the figures as directed, you are led to con¬ 
clude that an organ is a particular part 
of the body; and when you recall what 
you already know of the work of the or¬ 
gans, like the heart, you will come to the 
conclusion also that each organ has a par¬ 
ticular duty to perform. Thus, for ex¬ 
ample, the heart is an organ that pumps 
blood. Mention some other organs and 
tell what you think their duties are. Now, 
define organ 
in your own 
words. 

The ch i e f 
organs of the 
body may be 
located by a 
study of Figs. 

80a, 80b, 80c. 

The brain and the spinal cord 
are seen to occupy the dorsal cav¬ 
ity, so called because this cavity 
is located on the dorsal or “back” 
side of the body. The ventral cav¬ 
ity (the large cavity on the ven¬ 
tral or “front” side of the human 
body) is separated into the thoracic and the abdominal cavi- 




Fig. 80b. — Diagram 
showing the princi¬ 
pal cavities of the 
body. 






126 


The Human Body and Its Enemies. 


ties by the diaphragm. Above this partition are the heart and 
the lungs that have to do with the pumping of blood and 
breathing respectively. Below the diaphragm are the organs 
that have to do with digestion and other functions. 

Finer Structure of the Organs. —Each organ is in turn com¬ 
posed of parts called tissues. There are different kinds of tis¬ 
sues, and each kind has a particular work to do 
in the organ. Take, for example, a piece of beef. 

The soft, red part is muscle tissue ; it is the main 
tissue that goes to make up organs called mus¬ 
cles. But muscle tissue is very tender, and would 
not hold together by itself. The tissue that binds 
muscle tissue together is tough and pliable, and 
is found in all muscles; it is called connective 
tissue. This may be seen as glistening white 
strands in beef or other lean meat. It also serves 
to bind muscles to bones and bones to each other. 

The sinews or “leaders” in the legs of deer were 
used by the Indians for bow-strings on account 
of their toughness, for they consist of connective 
tissue. In the muscle shown in Fig. 81, the part 
at A consists mainly of connective tissue; at B, 
mainly of muscle tissue; at C, of about an equal 
amount of each. Other white strands often seen 
in a piece of meat are nerves, which consist of 
nerve tissue. Thus a muscle is an organ consisting of muscle 
tissue, connective tissue, nerve tissue and other tissues not so 
easily seen. 

Observation Work.—Secure a piece of “soup meat” or other 
tough meat from around a bone, and let several pupils each 
take a small piece and “dissect it.” To do this lay the specimen on a 
board or an old newspaper and pick it to pieces with a knife or sharp 



Fig. 81. A 
muscle. 









The Body a House of Many Parts. 


127 


sticks. How many kinds of tissue can you find? Let all of the pupils 
see them. Describe the kinds of tissue that you can readily see. 

Cells. —Our study does not end here, however. With the 
unaided eye we cannot find out anything more about the tis¬ 
sues; but with the aid of the microscope men have been able 



Fig:. 82. Different kinds of cells: A and B, muscle cells; C, fat cells; D. 
connective tissue cells; E and F, epithelial cells; e, a single cell; a, end 
view of flat cells. 


to discover that the tissues are themselves composed of very 
tiny parts called cells. A muscle-cell from the arm would 
look something like Fig. 82 A, under the microscope. An¬ 
other kind of muscle cell is shown at B. Connective tissue 
cells are shown at D. Some of the cells are very long and are 
called fibers; some are of more nearly equal length and thick¬ 
ness like grains of rice or corn; some are large and full of fat 
and are called fat cells. Tissue that consists largely of fat 
cells is called fatty tissue, and is pictured at C. 

Observation Work.—To get an idea of what a fiber looks like, take 
a sheet of good smooth writing paper. Tear off a corner and examine 
the torn edge, holding it between the eye and the light. The 
frazzled edge shows tiny fibers, comparable to the fibers of muscle 
and connective tissue. 







128 


The Human Body and Its Enemies. 


Even these tiny cells, some of which are so small that hun¬ 
dreds could find room on the point of a pin, are in turn com¬ 
posed of definite parts. These parts are (1) the body of the 
cell, and within that (2) a denser portion, the 
nucleus, as shown in Fig. 83. 

Another kind of tissue is one called epithelial 
tissue (Fig. 82 e), and the use of this in the 
body is to cover surfaces or to form glands. 
You can easily imagine the shape of cells in 
this tissue. They w T ould not be long like con¬ 
nective tissue or muscle fibers, but more like 
cubes or cylinders or discs (Fig. 82 e). It is 
sometimes called pavement tissue. This expression is good, 
as it compares the tissue to a pavement or a tiled floor. The 
individual bricks or blocks or tiles of the pavement would 
be compared to what in the epithelial tissue? Diagram E in 
Fig. 82 pictures some very flat epithelial cells scraped from 
the inner surface of the cheek as they appear under the mi¬ 
croscope, much enlarged. At B is seen their appearance in 
end view, which serves to show how flat they are. The outer 
horny skin is an epithelial tissue, ten or more cells in thick¬ 
ness. 

The body is thus a colony of cells and may be compared to 
a brick building which is made up of so many individual 
bricks. Just as from a distance we cannot distinguish the in¬ 
dividual bricks of a house, so also we cannot distinguish the 
cells of the body until we examine its tissues with the aid of a 
microscope. The microscope makes these tiny objects look 
hundreds of times as large as they really are. Without it we 
should still be ignorant of much of the wonderful structure 
and work of our bodies that we now know. 



Fig. 83. A cell, 
showing nuc¬ 
leus, N. 






The Body a House of Many Parts. 


129 


Summary. 

The body consists of myriads of tiny cells mat 
cannot be seen without the aid of a microscope. Cells are of 
different kinds, but similar cells combine to form a tissue. Tis 
sues combine to form organs. Each tissue has a particular duty 
to perform in the organ: muscle tissue to contract and move the 
body, connective tissue to bind parts together, epithelial tissue 
to cover surfaces. Other kinds of tissues will be studied in later 
chapters. 


Questions. 

1. When I say, “The heart pumps blood,” is this a statement of 
the physiology or the anatomy of the heart? 2. What is meant by 
physiology? 3. Anatomy? 4. Hygiene? 5. Sanitation? 6. What is 
an organ? 7. Name the cavities of the body. 8. Name and locate 
the important organs of the body shown in Figs. 4 and 5. 9. Tell 

how the microscope bas been of service to mankind. 10. Describe 
muscle tissue; connective tissue; a cell 11. Draw pictures of sev¬ 
eral kinds of cells. 


CHAPTER XIX. 


Why We Eat . 

All the tissues of the body are built up out of the food we 
eat. This is one of the most mysterious things in all nature: 
how the simple articles of food which we eat day by day be¬ 
come transformed into* the various tissues and cells which 
make up our bodies. To understand these wonderful things 
better, we must study the different foods we eat and their 
special uses. We wish to learn which foods build up the tis¬ 
sues and which have value to us in other ways. 

All Animals Need Food. —Have you ever observed a mother 
bird feeding her little ones in her nest? How wide they open 
their hungry mouths and utter eager cries, while the devoted 
mother brings one worm, insect or seed after another to ap¬ 
pease their appetites! What would happen to the helpless 
nestlings if the mother bird were killed is easy to imagine— 
they would starve to death. All animals must have food. You 
who eat your daily meals with regularity have perhaps not 
thought of the way animals have to struggle for a living, for 
they, like you, are always hungry. Consider how the follow¬ 
ing animals secure their food in the wild state: cats, wolves, 
deer, fish, birds, spiders, boll weevils, mosquitoes, bees, owls. 
Discuss them in class. A large part of an animal’s time is 
spent securing food. The same is true of man. A refer¬ 
ence to your text-book of geography will show you what a 
large part of man’s time is spent in the raising, selling and 
transportation of plants and animals for food. 

Why We Need Food. —If asked why we need food, different 
persons give different answers. “To nourish the body,” “To 




Why We Eat. 131 

give us strength,” “To keep us alive,” are among the answers 
one hears. Perhaps we may find simpler answers to the 
question why we eat. 

The nestling bird is small and featherless, the puppy has 
many pounds yet to gain in weight, and you are not as large 
as you expect to be. Young animals and boys and girls 

eat to grow. 

And yet we do not gain in body weight according to the 
weight of the food we eat. If you eat two pounds of food a 
day, how much do you eat in a year? In an average lifetime? 
Why, then, do we eat so much more than is needed for growth ? 

Perhaps if you were asked why you feed your horse more 
when he works than when he is idle; or if you were asked 
why you are unusually hungry after vigorous exercise you 
might answer that we eat to work. In other words, food fur¬ 
nishes energy—it enables us to work. 

How, then, does the food furnish us energy ? To answer this 
question let us first ask whence comes the energy to run a 
steam engine? From the wood that is burned under the 
boiler, you say. The stored-up energy placed in the wood by 
the tree is changed into active energy, heat, by the burning. 
The carbon in the wood unites with the oxygen of the air and 
in so doing produces heat. This uniting of oxygen with sub¬ 
stances is called burning or oxidation. 

Experiment With Carbon.—You have all seen charcoal. This black 
substance is an example of carbon. Coal is also largely carbon; and 
so is the “lead” of your lead pencil. Strike a match and let it burn 
until it is well scorched, then blow it out. The black you now see is 
carbon. There is, therefore, carbon in wood. Carbon will burn by 
uniting with oxygen, forming carbon dioxide. The carbon dioxide 
passes off into the air. Strike another match and as it burns state 
what happens. 


132 


The Human Body and Its Enemies. 


In a similar way the body gets its energy from food. Green 
plants produce foods of various kinds, which are eaten by ani¬ 
mals. Animals breathe in oxygen with the air just as a stove 
or a boiler of the engine takes in oxygen in the draft. In the 
body, as in the engine, the oxygen unites with the carbon 
which the food or fuel contains, and energy 
is given off—we are firstly enabled to do 
work, and, secondly, we are kept warm. The 
more we work the more we must eat. The 
faster we exercise the faster we must 
breathe to supply us with sufficient oxygen 
to “burn,” and as a result of this increased 
oxidation our bodies become warmer. In all 
this our bodies are like engines. We may, 
therefore, say that we need food to supply 
our bodies with energy for work and with 
heat to keep our bodies warm. 

In one regard, however, our bodies differ 
from an engine: the engine cannot repair it¬ 
self. If a part breaks or wears out a new part must be sup¬ 
plied. Every part of the body is constantly wearing out, but 
the body repairs itself. In case of injury to the skin, new skin 
soon covers the wound. If a bone is broken, the fracture heals. 
Hair and nails and skin are continually growing to take the 
place of cells worn off. We need food, therefore, also to repair 
worn-out parts of the body. 

Plants, Too, Need Food. —Plants are living things, just as an¬ 
imals are, and they, too, need food. Plants use food 
rather for growth, while boys and girls need it more 
for energy to get about with in their work and play. Think of 
how an acorn grows to be a giant oak. In a wonderful way 
all of the roots, trunk, limbs and leaves of the tree are built 



Fig-. 84. Diagram 
illustrating: the 

formation of the 
starch in green 
leaves. 





Why We Eat. 


133 


up out of water and a few minerals from the soil and carbon 
dioxide from the air. The green part of leaves has the power 
of making starch out of water and carbon dioxide with the aid 
of sunlight, as indicated in the diagram, Fig. 84. How this is 
done and what the plant does with the starch in building up 
its own body you will learn when you study botany or agri¬ 
culture. Animals and man make use of the starch and other 
substances in the plants, using them for food and thus indi¬ 
rectly also using the warmth of sunlight for their own bodies. 


Summary. 

Green plants, with the energy of sunlight, manufacture foods 
for animals and man. This food furnishes energy, enabling us 
to move about in work and play and keeping our bodies warm. 
The food containing carbon will burn like wood or coal by 
uniting with oxygen from the air. Food also furnishes mate¬ 
rial for growth and for the repair of injured or worn-out parts 
of the body. 


Questions. 

1. Make a list of the names of animals, and place opposite each 
the name of the chief kind of food the animal lives on. 2. Name 
four reasons why we need food. 3. Do we need more food in winter 
or in summer? Why? 4. Why do we need more food when we exer¬ 
cise than when we rest? 5. What kind of substance is carbon? 6. 
Name some substances that contain carbon. 7. What is the use of 
carbon in our foods? 8. What part do plants play in nature? 


CHAPTER XX. 


What We Eat . 

All animals depend directly or indirectly upon green plants 
for food. Most animals live upon plants directly, as cattle, 
potato-beetles and plant lice. (Mention five others.) Some 
animals prey upon other animals, as wolves upon sheep and 
rats upon mice; but in each case the prey gets its food from 
green plants and so the wolf and the cat are dependent in¬ 
directly upon plants. Man eats both plant and animal food. 
Do you know of animals that do the same? Consulting your 
geographies, make a list of five important animals used by 
man for food, and where these are raised; ten important 
plants, and where these are raised. Make a list of twenty-five 
food products that you can buy at the grocery store. These 
studies will convince you that there are many kinds of food. 
Even the same animal will produce various kinds, as cattle, 
which furnish meat, milk and cheese. So all food of man 
comes from living things. 

All of these kinds of food are really made up of but three 
classes of food substances. That is, all of the foods placed 
on the table before us to eat, or that we feed to our domestic 
animals, are mixtures of these classes: carbohydrates, fats 
and proteids. Carbohydrates, fats and proteids are called the 
foodstuffs, and these make up all of our food, whether derived 
from plant or animal. 

The Carbohydrates, the sugars and starch, we get almost 
altogether from plants, and they are the cheapest of the food¬ 
stuffs. Starch is found in large amounts in most seeds, such 
as corn, rice, wheat, beans and peas; in the stem of the sago 
palm (sago) ;. in roots and underground stems of manioc 


What We Eat. 


1 35 


(tapioca), sweet potato, Irish potato. Sugars are of different 
kinds: cane sugar, secured from sugar cane and sugar beet; 
and grape sugar, found in grapes and other fruits, but manu¬ 
factured from cornstarch in large amounts. Cane syrup (mo¬ 
lasses) and corn syrup, contain chiefly sugar and water. 
Honey and the sap of maple trees are also sources of sugar. 
Sweet corn and milk and most fruits contain some sugar. 

Experiment With Starch. —One can easily find out whether a 
substance contains starch or not. Iodine turns starch blue. Make 
a thin starch paste by boiling a little starch in water. Add one 
drop of tincture of iodine (to be secured from any drug store) to 
a little starch paste in a test tube or a small bottle. Try this on 
crumbs of bread shaken up in water. Place a drop of the solu¬ 
tion on a cooked potato; on a raw potato; on an apple, or on any 
other food you want to test for starch. 


Experiment With Sugar. —If food is sweet it contains either cane 
sugar or grape sugar. The latter is easily found if present, be¬ 
cause it causes a red color to appear when heated with Fehling’s 
solution. Fehling’s solution is a mixture of two solutions: A, a 
solution of bluestone, and B, a solution of soda lye. The solutions 
should be kept separate until they are used. They can be secured 
at the drug store and should be fresh. Grape sugar is found in 
corn syrup and cheap stick candy. Dissolve some of either in water. 

When ready to make the test, mix 


FIG. 85. 


FIG. 86. 



a quantity of Fehling’s solution, 
by using equal parts of solutions 
A and B. Pour the mixed solu¬ 
tion into a test tube to the depth 
of an inch. Bring to a boil, using 
an alcohol lamp and applying the 
flame to the top of the liquid, as 
shown in Fig. 85. Now add about 
fifteen drops of a solution of stick 
candy. The red color which will 
appear indicates grape sugar, for cane sugar will not act that way. 
Try this also on cheap cakes to see what kind of sugar was used 
in their manufacture. 



Figs. 85 and 86. Showing two 
methods of heating liquids. 



136 


The Human Body and Its Enemies. 


Experiment to show how grape sugar is made from starch.—Add 
a little hydrochloric acid to some thin starch paste in a test tube 
and heat it. Note that the liquid becomes clear. Test for sugar as in 
the last experiment. The acid has turned the starch into grape sugar. 

Some Foods Rich in Fat. —Animals produce fats in their 
bodies. Meat, therefore, has more or less fat, that of beef 
being called tallow; of pork, lard. The cream of milk is fat; 
cheese, being made from milk, contains considerable fat. The 
yolk of eggs is largely fat. Nuts are usually rich in fats, as 
also are the seeds of the cotton plant and peanut and the fruit 
of the olive. There is not much oil in the grains, but corn con¬ 
tains more than the others. A fat that is liquid at ordinary 
temperatures is called an oil. Thus tallow is a fat; cotton 
seed oil is an oil. 

Some Foods Rich in Proteids. —In selecting a meal we would 
not choose potatoes to go with bread and butter, but rather 
eggs or meat. Bread and potatoes furnish starch chiefly, and 
eggs and meat are largely proteid.* The white of an egg, called 
albumen, is almost pure proteid, as is also lean meat. Milk 
is rich in proteid. In skimming milk we remove only the fats, 
leaving the proteid and sugar. The curd of the milk is the 
proteid. Seeds of the legumunous plants (peas, beans and 
peanuts) are very rich in proteids. Among the common grains, 
wheat contains most, rice least proteid. 

Experiment With Proteid.—Shake up a very little white of egg 
in a test tube with some twenty drops of water. Add ten drops of 
concentrated nitric acid and warm the mixture over an alcohol flame. 
A yellow color appears. Add ammonia until effervescence ceases. 
The orange color that appears indicates the presence of proteid, in 
this case the white of egg. Try this on bread crumbs or other 
food. 

Observations on Grains of Rice, Wheat and Corn.—Soak in water 
for twenty-four hours enough grains of rice, wheat and Indian corn 
to supply one or two of each kind to each pupil in the class. If 


What We Eat. 


137 


needed at once the seed may be boiled for a short time. Note the 
location of the germ or embryo (E) as shown in the outline 
sketches in Fig. 87. With a sharp knife cut the grains lengthwise 
through the germs along the straight lines indicated in the drawings. 
Study the cut side; make out the germ in the corner and the pro- 
teid and starch portions of the grain The starch will be found 
white and softer than the more shiny and horny proteid portion of 



Fig. 87. Sections through seeds of rice (I), wheat (II) and corn (III), 
showing the proteid (P) and the starch (S) of the seeds, and their 
germ (E); 1, 2 and 3, the seeds as seen from the outside, natural size. 


the seed. What kind of corn is it more profitable to raise: corn 
with seeds rich in starch or corn with seeds rich in proteid? 

The Uses of the Various Foodstuffs in the Body. —All of the 
foodstuffs serve to produce heat in the body and energy for 
work, because all contain carbon for burning.* Fat is the 
best “fuel food” because it will produce the most heat and 


*You may easily prove that there is carbon in proteid and in 
starch and sugar by scorching them (in frying an egg or baking 
bread, for example). The black substance is carbon. 







138 


The Human Body and Its Enemies. 


energy in the body. In what season of the year are fats most 
palatable, fat pork for example? In what region of the globe 
are fats and oils considered delicacies? Carbohydrates and fats 
serve only to produce heat and energy and are therefore 
called “fuel foods.” Proteids serve this purpose also; but 
in addition to this they are the “tissue builders,” that is, 
they are used for growth and repair of the living substance 
in the body. 

Other Things Needed by the Body. —We prefer to call only 
those substances food that will burn, or that can be oxidized 
in the body. But for life and health other substances of the 
mineral kingdom are necessary. Oxygen is needed by all living 
things. It is found mixed with nitrogen in the air. We cannot 
live over a few minutes without breathing in a new supply of 
oxygen. It is needed to burn up the food in our bodies and to 
keep up the “fire of life.” Water is almost as necessary for 
the body as oxygen. Almost three-fourths of the body is water. 
Besides drinking the water we get a great deal of it in our 
food. Over eighty per cent of potatoes, for example, and fifty 

per cent of beef consists of wa¬ 
ter. Mineral salts, particularly 
table salt, are essential to the 
proper working of the organs 
of the body. Lime is necessary 
for the bones, especially during 
growth, and iron -for the red 
corpuscles. All of these miner¬ 
als, except table salt, we usu 
ally find in sufficient amounts 
in our food. For example, all plants contain some lime, and 
iron always forms one of the constituents of green leaves. 

Experiment to show that foods contain mineral matter.—Take 



Fig. 88. Ash is the mineral part 
of food. 



What We Eat. 


139 


a piece of bread or meat, place it on a piece of tin, or, better, in an 
iron spoon (Fig. 88) and burn it over a fire. Examine the ashes. 
They are the mineral matter in the food. 


Summary. 

There are many kinds of foods that serve for man and beast 
the world over, some derived from plants and some from ani 
mals. These contain only three classes of foodstuffs: carbohy¬ 
drates (sugars and starch), fats and proteids. Carbohydrates 
and fats are called the fuel foods since they serve only to be 
oxidized or burned in the body for the production of heat and 
energy. Fats are the best heat-producing foodstuffs. Pro¬ 
teids equal starch and sugar as a fuel food, but in addition 
build up the tissues, being used in the body for growth and 
repair. Certain minerals must also be taken with the food 
for the maintenance of health. 

Questions. 

1. Mention ten common foods. 2. Mention the main foodstuffs. 3. 
Are animal or vegetable foods the richer in carbohydrates? 4. Men 
tion four foods rich in fats; six rich in proteids; eight rich in car¬ 
bohydrates. 5. How can you test a food to find out if it contains 
starch? 6. What is the test for proteids? 7. Which foodstuff is 
the only tissue builder? 8. Why can all the foodstuffs furnish 
working energy and heat? (See question 7, Chap. XIX.) 9. Which 
is the best fuel food? 10. What should be a difference in the 
kind of our food in summer and in winter? 11. Mention the most 
important mineral foods. 12. How can you prove the presence of 
minerals in food? 


CHAPTER XXI. 


Pure Food . 


To select foods wisely for a meal we should remember sev¬ 
eral important things: what foodstuffs the foods contain, for 
whom they are intended, whether or not they are free from 
disease germs, and how to get the greatest value for one’s 
money. 


A Mixed Diet. —Everyone knows that a person cannot live 
on eggs alone, and you now know that the reason is because 
eggs do not contain carbohydrates. All 
of you like candy, but you would soon 
grow tired of candy and ask for plain 
bread and butter and meat. It is not 
a good idea to live on any one kind of 
food. In other words, we need a 
“mixed diet.” Milk contains all of the 
foodstuffs and is an excellent food; but 
it does not contain them in the right 
proportion. As a rule, we need twice as 
much proteids as fats and nine times as 
much carbohydrates as fats. 

The proteids are especially useful for building up our bodies, 
and growing children need plenty of proteids. Any one who 
is recovering from a spell of sickness will need much proteid 
as soon as it becomes safe for him to have it. Of fats we 
should eat more in cold weather than in w T arm, for reasons 
stated in a previous chapter. Starch and sugar are useful 



Fig-. 


Refrigerator. 
Food should be kept 
cold to prevent decay. 











Pure Food. 


141 


to furnish working energy and warmth. They should make 
up the bulk of what we eat. 

*Eating Habits. —Now, let us talk of something particularly 
practical, and something you can remember easily. How many 
meals a day do you have at home? Three? Why do people 
usually have three meals a day? It is probably habit, and it is 
a fairly good habit, but surely not all of us are exactly alike; 
for there are some boys especially that get hungry between 
meals and often eat candy. Children ought to eat between 
meals if they get hungry. They should be trained gradually to 
habits of regularity, but each pupil should be treated accord¬ 
ing to his own needs. Children can be trained to take a sand¬ 
wich or a slice of buttered bread between meals instead of the 
candy they so often want. Candy is harmless in moderate 
amounts, but is best eaten at a regular hour when other food 
is taken. Colored candy is harmful in many cases. 

The Cost of Foods. —The foods that cost least per pound 
are not necessarily the cheapest. Thus corn meal is cheaper 
than wheat flour, but it contains less proteid. In purchasing 
food we must take into consideration the amount and the pro¬ 
portion of the foodstuffs as well as the price per pound. 
Cheese is more nutritious than oysters, and cheaper. Peas 
and beans are very cheap and nutritious articles of food. 
It is necessary, however, to take into consideration also the 
individual tastes in the matter of selecting foods, as food must 
be appetizing and must “agree” with a person to be of 
greatest value. 

Buying Food in the Market. —We now come to a subject of 


♦Many children do not take sensible lunches to eat at school, but 
buy candies and pastry instead. This habit is bad and leads to in¬ 
digestion and to poor progress in a pupil’s studies. 



142 


The Human Body and Its Enemies. 


especial interest to the girls. The place where most can be 
done in improving our food is in buying it at the market. 
There are many good things to eat that can be bought if you 
only go to market to find them. But if you merely telephone, 
the market man will, of course, see that you are not particular 



Fig. 90. Cooking- is so important that the subject is taught in many 
schools. 


and will send poor food. He may have some good vegetables 
that you would like if you saw them, but he does not know 
you desire them, and in fact you do not. But if you saw them 
you might want them instead of something else. In buying 
always say, “Let me see it first.’’ 

If you are too busy to go to market, then always inspect the 
food as soon as it is received and return that which is not 








































Pure Food. 


143 


fresh and good. The market man will furnish just as good 
food as the women demand. There is plenty of good food ma¬ 
terial to be had in Texas, and if our housekeepers pay atten¬ 
tion to the food as it is bought they can get good food. In 
buying fish and meats especially, great care is necessary; also 
in buying fruits and vegetables. Think of the number of over¬ 
ripe tomatoes that are placed on the table in Texas in the 
course of a year. The only way to avoid this is by looking at 
the tomatoes closely, and this should be done at the time 
they are bought. Those who 
are interested may learn the 
names of the cuts of beef 
from the numbered diagram, 

Fig. 91. 

Lucretia Borgia, an Ital¬ 
ian noblewoman, was said to 
have poisoned many people, 
but they were her enemies. 

We poison people today, but 
they are our friends and 
guests. We do it from care¬ 
lessness in selecting the food. 

Have you not heard of the dreadful ptomaine poisoning 
which kills so many people, especially after they have eaten 
fish? Many of these cases could have been prevented by 
a little care in inspecting the fish when they were bought. 
Many of you say that you do not know how to tell good 
fish or meat when you see it. But if you try, you will 
find that you can do so. There is a fresh fishy 
odor about all fresh fish, but there is a putrid 
odor, an odor of decay, which surrounds the decay¬ 
ing fish. 



Fig. 91.—The cuts of beef: 1, 
neck; 2, chuck; 3, ribs; 4, shoul¬ 
der clod; 5, fore shank; 6, bris¬ 
ket; 7, cross ribs; 8, plate; 9, 
navel; 10, loin; 11, flank; 12, 
rump; 13, round; 14, second cut 
round; 15, hind shank. 








144 


The Human Body and Its Enemies. 


Canned Foods. —Canned fish and canned meats are danger¬ 
ous, because a pinhole, too small to be seen, may allow germs 
to get in and cause the decay of the meat. Dr. Wiley says that 
canned vegetables are not dangerous as a rule, but that 

canned fish and canned 



Fig. 92. “Swell head.” Bacteria 
sometimes cause decay of canned 
foods, especially meats; the can 
may “swell” from gases on the 
inside. 


and some uneasiness. Some- 


meats are always subject to 
suspicion. A young man in 
Austin ate some canned sal¬ 
mon at 3 o’clock one after¬ 
noon, and died of ptomaine 
poisoning the next morning. 
Many people are thus made 
sick but do not die. The 
canned goods, however, 
should be eaten with care 


times canned goods in pu¬ 
trefying form a gas which 
presses out the top and bot¬ 
tom of the can, causing what 
is known as “swell head.” 
(Fig. 92.) It is unnecessary 
to say that such a can should 
be strictly avoided. Canned 
vegetables are more of a ne¬ 
cessity in the North than 
they are here. Texas needs 
some progressive men to de- 


Mt** 





velop the various vegetable industries just as the onion in¬ 
dustry has been developed in the Laredo country. 


Cooking. —Most foods are improved by cooking (baking, 
boiling, broiling, stewing, etc.) for the following reasons: 







Pure Food. 


145 


M\j»cLt n#e«s 



1. Heat destroys the bacteria, which you have learned are 
likely to be present in food. It also destroys certain worm 
parasites like trichina in pork (Fig. 94), or 

tapeworm larvae in pork and beef (Fig. 93). 

2. Cooking makes most foods more appe¬ 
tizing. An appetizing appearance and pleas¬ 
ant flavor of foods aid digestion in that they 
stimulate the digestive glands. 

3. Cooking usually renders foods more eas¬ 
ily digestible. In the case of vegetable foods 
we find that the plant cells have very thick and 
undigestible walls, and that the starch and 
proteid grains (Fig. 95) have tough skins 
around them. Heat breaks up the starch grains 
and the plant cell (Fig. 96), so that the digest¬ 
ive juices can get to the food material. In the 
ease of meats, heat causes the connective tissue 
to swell and soften, but it does not make the 

muscle tissue of the 
meat more digest¬ 
ible. 

It should be re¬ 
membered that heat 
hardens proteids like 
muscle tissue and the 
white of eggs and 
makes them harder 
to digest. White of 
eggs is more easily 
digested soft boiled 
foods less digest- 


Fig. 94. A trich¬ 
ina from a 
muscle of the 
eyelid. 


FIG. 96. 



ATARI 

4RAINA 


Figs. 95 and 96. Uncooked and cooked potato 
cells, magnified. 


than 

ible. 


hard boiled. Grease renders 




146 


The Human Body and Its Enemies. 


Milk as a Food. —Milk is one of the most nourishing of all 
foods. It forms an especially large part of the food of young 
children, old people and invalids. Milk contains all of the 
foodstuffs in nearly the right proportions. When intended for 
babies under two years old, milk should be prepared by adding 
certain foodstuffs to it to make the proportions exactly right. 
This should be done under the advice of a phsician. Babies 
do better on cow’s milk than on the patented foods adver¬ 
tised. Since, then, milk is so important as a food it behooves 
us to see to it that our milk supply is clean and pure. 

Bacteria in Milk. —Because milk is very nourishing bacteria 
will thrive and multiply in it after they once get a start. 
There are many adulterants which dishonest people add to 
milk; but the most dangerous things that we find in the milk 
are the harmful bacteria. More epidemics of disease have 
been spread by milk than by any other food. Up to 1909, 
two hundred and eighty different outbreaks of disease had 
been definitely traced to milk as a cause of spread. Most of 
these were typhoid fever epidemics, but scarlet fever and 
diphtheria also occurred in epidemic form because of the pres¬ 
ence of disease germs in milk. Milk is especially connected 
with tuberculosis, because cattle are affected by that disease, 
and tuberculosis is the commonest disease in the world. In 
view of these facts it is well to learn how milk can be kept 
free from dangerous germs. 

The Cow. —First, the cow herself must be healthy. In many 
states, one-fourth of all milch cows are affected with tubercu¬ 
losis. In Texas, however, the tests made by the Dairy and 
Food Commissioner show that only one cow in a hundred 
is affected. Children can contract bone and gland tu¬ 
berculosis from germs in milk, and hence they should never 


Pure Food. 


147 



drink milk from cows that have not been tested and found 
to be free from tuberculosis. The most healthy looking cow 
may have the 
disease. Fig. 97 
shows a cow in 
apparently good 
condition, b u t 
when tested she 
was fonud to 
have tuberculo¬ 
sis. 

Milking. — In 

milking we 
should do all 
we can to pre¬ 
vent bacteria 
from getting into the milk. 

Most bacteria are, of course, 
kinds that are harmless un¬ 
less present in very large 
numbers. So great care of 
the milk should be taken, so 
that in twenty-four hours 
there should not be more 
than 300,000 bacteria to the 
thimbleful. If carelessly 
handled the milk may be a 
“germ soup,” containing 3,000,000,000 to the thimbleful. There 
are several points important to remember in milking: 


Figr. 97. This cow, though healthy in appearance, 
was found to have tuberculosis. 


FIG. 98. 



8 AO MILK PAIL. 6000 MILK PftIL 

Figs. 98 and 99. A bad and a good 
kind of milk pail. 


(1) No person who has had typhoid fever within twelve 
months should be allowed to handle the milk, unless a physician 
has made a test and pronounced the patient free from danger- 




148 


The Human Body and Its Enemies. 


ous germs. A “typhoid carrier” would infect the milk with 
his hands. Every milker should wash his hands with 
soap and water before milking. (2) Dust carries many bacteria 
into milk. To prevent this the cow’s udder should first be 
washed. A milk bucket with a small opening, as shown in Fig. 
99, and not one of the kind shown in Fig. 98, should be used. If 
the milk is intended for the baby, it is well to milk through 
a scalded cheese cloth stretched over the bucket. It is, of 
course, needless to add that flies should be kept from wiping 
their feet on any of the milk vessels. 

Care of the Milk. —Germs will not grow and multiply rapid¬ 
ly in the cold. The warm milk from the cow should be cooled 
at once after straining, 
and should be kept on ice. 

In case ample cooling fa¬ 
cilities are not at hand, at 
least milk intended for 
the baby should be kept 
cold until it is to be used, 
when it can be quickly 
warmed. Fig. 100 shows a 
simple, inexpensive form 
of a home-made ice box. 

The milk room should be screened and free of flies. 

Dairy Inspection. —When a person owns his own cattle, it is 
a comparatively simple matter to have everything connected 
with the care of the milk clean and sanitary. Those who get 
their milk from a dairy, however, find it hard to get milk that 
has fewer than 300,000 bacteria in a thimbleful. It is well to 
patronize a dairy that you know is sanitary, and it is well to 
pay the dairy an occasional visit. The women’s clubs can do 



Fig. 100. A home-made ice box for keep¬ 
ing bottles of milk cold and sweet. 





Pure Food. 


149 


a great deal to secure proper laws for the regulation of the 
milk supply and to see to it that these laws are enforced. 

Summary. 

In leaving this chapter remember the following points: 

1. Care should be taken in the selection of food. In plan¬ 
ning a meal we should select a variety of foods so that all of 
the foodstuffs be represented. 

2. Above all, we should select food free from disease germs. 

3. Canned foods should be looked upon with suspicion, for 
they often contain poisonous germs. 

4. Cooking kills germs and makes many foods, particularly 
most vegetable foods, more digestible and more palatable. 

5. Milk is so important a food and so often contains dan¬ 
gerous germs that every care should be taken to secure pure 
milk. 

6. Milk is infected with dangerous germs from dust, from 
flies and from the milker’s hands and throat. 

7. Germs usually harmless may become harmful to children 
and invalids when present in numbers more than 300,000 to the 
thimbleful. 

8. Milk should be drawn into a bucket covered with a 
scalded cheese cloth, and should be strained and put on lcb 
at once. 


Questions. 

1. What is meant by a mixed diet? 2. Select for a dinner five 
foods that shall together constitute a mixed diet. 3. Why is it bet¬ 
ter to eat something substantial for a school lunch than mere candy 
or pie? 4. What are the most harmful things that get into food? 
5. Discuss the danger from canned foods. 6. State three advantages 


150 


The Human Body and Its Enemies. 


of cooking food. 7. What foods should be cooked long and at a high 
heat? 8. Why is milk an important food? 9. Why may milk be 
also a dangerous food? 10. What diseases are known to be scattered 
by infected milk? 11. Why should milch cows he tested for disease? 
12. Discuss fully how we can prevent bacteria from getting into 
milk. 13. Why should milk be kept cold? 14. How could you 
make a cheap ice box sufficiently large for keeping several bottles of 
milk? 15. What does Fig. 97 illustrate? 


CHAPTER XXII. 


Getting the Food Heady for the Blood: Digestion. 


The proper selection of the food in the market and its prep¬ 
aration in the kitchen is important; but the food is even then 
not ready for the blood. In the mouth and the food-tube the 
food is changed very much. It is ground up, mixed with juices 
and becomes quite liquid before the blood receives it to carry 
it to all parts of the body. The following experiments should 
be performed to illustrate the changes the food undergoes in 
the body: 

Preliminary Experiments.— (1) Take two tumblers half full of 

water. Into one place a lump of salt (table salt); into the other 
drop the same amount of salt that has first been powdered by grind¬ 
ing in a mortar or with the head of a hammer on 
a smooth board. In which tumbler does the salt, 
dissolve the faster, and why? To another tumbler 
add a little starch. Does this dissolve like the salt? 

The salt is said to be soluble; the starch insoluble. 

(2) Again procure three tumblers with water, 
a quantity of hydrochloric (muriatic) acid and two 
small pieces of limestone or marble about the size 
of a pea. Drop one piece of limestone into tumbler 
No. 1 (Fig. 101). To both the other tumblers add 
a little acid. To tumbler No. 2 add a piece of 
marble in a lump; pound the other piece of marble 
to small bits and add them to tumbler No. 3. 

Tumbler No. 1 has water and a lump of marble 
only. Tumbler No. 2 has water and a lump of marble with acid. 
Tumbler No. 3 has water and fragments of marble with acid. Now 
observe the results. (Add acid to Nos. 2 and 3, if bubbling should 
cease before the limestone is dissolved). Putting together the re- 



Pig. 101. Lime¬ 
stone dissolv¬ 
ing- in acid. 



152 


The Human Body and Its Enemies. 


suits of the foregoing experiments we note: 

1. That salt is soluble. 

2. That starch is insoluble. 

3. That limestone is insoluble. 

4. That acid will change limestone into a form that is soluble 
in water. 

5. That salt in small particles is more readily dissolved than 
when in lumps. 

6. That limestone is acted on faster when in small particles than 
when in a lump. 

Digestion Defined. —The preparation of food in the body for 
the blood is called the digestion of food and may be compared 
to the action of acid on limestone in these experiments. The 
insoluble limestone is made soluble by the acid. In the exper¬ 
iment to illustrate the manufacture of grape sugar from starch 
(page 136), starch was digested by acid and heat. Digestion, 
then, may be defined as the process of rendering the food sol¬ 
uble in the body. 

Mechanical Digestion. —There may be said to be two sides to 
the digestive process. The experiments just described show 
us (see conclusion 5) that the limestone will be acted on faster 
when ground fine than when in a lump. Grinding up the 
limestone does not change it into a new substance, but simply 
makes the lumps smaller, for a piece of limestone is limestone 
still. Such a process is said to be mechanical. Thus we speak 
of mechanical digestion, the breaking up of the food into fine 
particles. This is performed mainly by the teeth, which cut, 
tear and grind the food into very small particles. (Fig. 102.) 
Chewing the food is extremely important. To eat a meal in 
a hurry, swallowing the food in large lumps (Fig. 103), is 


Getting Food Ready for the Blood: Digestion. 153 

very injurious and may cause indigestion and various other 
ailments. If food is improperly chewed, it is so slowly digested 
that it is likely to decay or 
sour before it can be fully 
.digested. Chewing is also 
good for the teeth, for un¬ 
less they are used a reason¬ 
able amount they will decay. 

In the mouth the food is 
also moistened with saliva, 
which aids in swallowing. To 
show how hard it is to swal¬ 
low dry food crush a small cracker and try to swallow it 
quickly. Then try one soaked in water. The churning 
motion of the stomach is also an important part of mechan¬ 
ical digestion. Note the direction, of the muscle fibers in 
the walls of the stomach shown in Fig. 114. 

Chemical Digestion. —When, however, in the experiment, 
acid has acted on the limestone, it is limestone no longer, but a 
different substance, and the new substance is soluble. Simi¬ 
larly, when starch is heated with an acid it is starch no 
longer, but is changed to grape sugar. Such a change is 
called a chemical change. In the body these changes are not 
brought about by strong acids or great heat, but by certain 
substances in the digestive juices, like the saliva in the mouth. 
The action of this juice on starch is the same as that of acid 
and heat: saliva changes starch to sugar. Such a change is 
called a chemical change, and the process in the body is called 
chemical digestion. The active agents of the digestive juices 
that bring about chemical digestion are called enzymes. Each 
enzyme acts on a single kind of foodstuff. For example, ptyalin 
is the enzyme in saliva that changes starch to sugar. The 



Figs. 102 and 103. Well chewed and 
poorly chewed food, magnified. 




154 


The Human Body and Its Enemies. 


most important enzymes are given in the table at the end of 
this chapter. The chemical digestion of starch by saliva can be 
studied very nicely in the following experiment: 

Experiments to prove that starch is changed to sugar by saliva.— 

(1) Taste a piece of clean wood; chew it a little. Does it taste 
sweet? Take a piece of cracker soaked in water and note whether 
it tastes sweet the moment it is taken into the mouth; or does it at 
first taste like wood? Chew it and note the result. Why does the 
wood not taste sweet as does the cracker after it is chewed a while? 

(2) Let one of the pupils chew half of a cracker for a few minutes. 
Have a small portion of the now nearly liquid contents of his mouth 
placed in a test tube. Add Fehling’s solution and boil as in the 
experiment on page 135. The red color proves that a large amount 
of sugar is present. 


° ^ . 

Q 


Fig. 104. Oil glo¬ 
bules in milk. 


Thus starch must be changed to sugar before the blood can 
take it up. Proteids are changed to soluble 
proteids called peptones. Fats are also di¬ 
gested. The first step in the digestion of 
fats is similar to the making of soap. In the 
making of soap, fat and lye are put into a 
pot and boiled. In the human intestine a 
kind of “soap” is made out of the fats of 
our food and soda there present. After some 
soap has been made this can digest more 
fat by “emulsifying” it, that is breaking it up into very 
small particles. Fat in this condition is called an emulsion. 
As an emulsion it can be taken up by the blood. 
Milk is a good example of an emulsion. A drop of milk seen 
under the microscope would show tiny drops of fat, as pic¬ 
tured in Fig. 104. 

Experiment to Illustrate How Fats Are Emulsified.—Take two pint 
bottles and pour a little oil (cottonseed oil will do) into each, so that 
some oil will stick to the sides of the bottles. To one add plain 
water; to the other, soap and water. Now let two boys shake the 
bottles. In which bottle do the oil and water mix well? In which 


Getting Food Ready for the Blood: Digestion. 155 

bottle does a layer of oil collect on top or continue to stick to the 
sides of the bottle? Why? 


Summary. 

Digestion of food in the body consists of changing insoluble 
into soluble foodstuffs: starch is changed to sugar, proteids to 
peptones and fats are emulsified. These changes constitute 
chemical digestion and are due to the various digestive juices. 
The process is hastened by the thorough chewing of the food, 
or mechanical digestion. 

The following summary of chemical digestion will prove 
helpful: 


Digestive Organ 

Juice 

Enzyme 

Digests 

Mouth 

Saliva 

Ptyalin 

Starch 

Stomach 

Gastric Juice. 

Pepsin 

(Rennin) 

Proteid 

(Curdles Milk) 

Small Intestine 

J 

1 

1 Pancreatic Juice 
| Intestinal Juice 

("Trypsin 
s Amylopsin 
LSteapsin 
(Invertin) 

Proteids 

Starch 

Fats 

(Cane Sugar) 


Questions. 

1. Define soluble; insoluble. 2. Mention several soluble and 
several insoluble substances. 3. What does Fig. 101 illustrate? 4. 
Describe an experiment illustrating digestion. 5. Define mechanical 
digestion. 6. Describe an experiment that shows the value of chew¬ 
ing our food. 7. What is meant by a chemical change? Illustrate. 
8. In the experiment with saliva, how can you prove that the starch 
has been changed to sugar? 9. Where are enzymes found, and what 
work do they do? 10. Name the digestive juices. 11. How are fats 
digested? 12. Mention the foodstuffs that have to be digested, and 
tell what each is changed into in digestion. 13. How can we study 
real globules of oil like those pictured in Fig. 104? 












CHAPTER XXIII. 


Where Digestion Begins : The Mouth. 


The organs of digestion are the various parts of the food- 
tube or alimentary canal and the several organs called glands 
that communicate with the alimentary 
canal. This begins at the mouth. The 
other organs can be seen in Fig. 80. 
Draw Fig. 105 on paper or on the 
blackboard, and, after comparing it 
with Fig. 80a, name the digestive 
organs on your drawing. 

The Mouth. —Name the organs found 
in the mouth. What bounds the mouth 
on the sides? in front? The roof of 
the mouth is called the palate (Fig. 
106) ; the hard palate nearer the front, 
can be touched by the tongue pressed 
upward; the soft palate, farther back, 
ends in a flap called the uvula. The 
mouth communicates behind with the 
throat or pharynx and is partly sepa¬ 
rated from this by the soft palate. 
Study Fig. 106. Then try to see the 
named organs in your mouth, hold¬ 
ing a hand mirror before you and 
standing toward the light. How large 
is the mouth cavity? To answer this 
question close the mouth and “feel” whether or not the 
tongue tills the mouth completely when closed. 



Fig. 105. Outline of the 
principal digestive or¬ 
gans. 





Where Digestion is Begun: The Mouth. 


157 


Chemical Digestion in the 
Mouth. —Review the chemi¬ 
cal action of saliva on starch. 
The saliva is produced by 
three pairs of salivary glands 
placed as shown in Fig. 107. 
These glands empty their 
juice, the saliva, through 
openings on the inside of the 
cheek (DP) and under the 
tongue (DS). A further use 
of saliva is to moisten the 
food to enable us to swallow. 
Saliva also keeps the inside 
of the mouth continually 
moist. 

The tongue is a muscular 
organ attached at its poste¬ 
rior end to the tongue-bone* 
(Fig. 133). Chew a mouthful 
of food and note exactly how 
the tongue “ handles’ ’ it. 
Place a little salt on the tip 
of your tongue; can you 
taste it without drawing the 
tongue back? What letters 
of the alphabet are made in 



Fig. 106. The mouth cavity. 



Fig:. 107. The salivary glands of the 
left side. 


♦You can feel your tongue 
bone by pressing tightly with 
thumb and index finger against the sides of the throat high up under 
the lower jaw. 






158 


The Human Body and Its Enemies. 


speech mainly by the tongue? by the lips? by the teeth? 
State three functions of the tongue suggested by these ques¬ 
tions. 

The teeth number thirty-two in the adult human beings— 
Fig. 109 gives the outlines and names of the teeth of the 
upper and of the lower jaw: two incisors, one canine, two 
premolars (or bicuspids) and three molars in each half jaw. 
Every person has two sets of teeth in his lifetime, those 
mentioned being in the permanent set. These begin to come 


FIG. 108. 


FIG. 109. 



Fig:. 108. The teeth of the lower jaw in place; the temporary, or “milk” 
teeth of one half of a jaw. 

Fig-. 109. The teeth of one side of both upper and lower jaws. 

at the age of five or six, pushing the earlier or temporary 
teeth out (the so-called milk teeth). Do you remember losing 
your milk teeth? When did you lose the last one? There are 
only twenty-eight milk teeth (eight incisors, four canines and 
eight molars, Fig. 108), enough for a small pair of jaws. As 
the child grows so does the jaw, and more teeth are needed. 
Since the teeth cannot grow, a new set is formed. Why do 
not all of the milk teeth fall out at once? How many teeth 
have you ? If you are between thirteen and twenty-one 
years of age you probably have twenty-eight, for the last 





Where Digestion is Begun: The Mouth. 


159 


molars (the “wisdom” teeth) do not appear before that 
time. 

With a mirror study the shapes of your teeth and deter¬ 
mine from their shapes what each kind of tooth is for: whether 
for cutting or for tearing or for grinding. How do the in¬ 
cisors of the lower jaw move over those of the upper in chew¬ 
ing? If possible, examine the incisors of a gnawing animal, 
as a rabbit, squirrel or mouse; the teeth of a dog or a cat; the 
molars of a horse or a cow. What is the relation of the shape 
of the teeth to flesh-eating or plant-eating habits of animals? 
According to his teeth what kinds of food is it natural for 
man to eat? 

Structure of a Tooth. —The only part of a tooth visible is 
the crown, which is covered with a hard, shiny substance, the 
enamel, the hardest substance of the body. The roots fit into 
sockets in the jaw bones. The gums cover the bones and 
come up a little distance on the tooth; this part of the tooth 
is termed the neck. The root is covered with a cement, a bony 
tissue, not so hard as the enamel. Underneath the enamel 
and cement, forming the bulk of the tooth, is the bone-like 
dentine, which surrounds the pulp cavity. This cavity or hol¬ 
low is open at the tip of the root and is filled with connective 
tissue, nerves and blood vessels. The relation of these parts 
can be understood better by reference to Fig. 110, or still bet¬ 
ter, by studying a section of a real tooth. 

Observation Work on a Tooth.—Secure a molar tooth of a horse 
or a cow (as these are large); or ask a dentist for a human tooth. 
A tooth not too old and dry is to be preferred. Have a black¬ 
smith saw this in two with a hack saw. Then for a few minutes 
vigorously rub the cut surface of each half on a whetstone, using 
plenty of water. The two halves should now clearly show the 
parts of the tooth. 


160 


The Human Body and Its Enemies. 


Care of the Teeth. —What are the uses of the teeth? Review 
the experiments on page 151 and state again the importance of 
chewing the food. The health of the other digestive organs, 
and therefore of the whole body, depends upon the preserva¬ 
tion of the teeth. Furthermore, since we have but one set of 
teeth for the rest of our lives after the thirteenth year, it be¬ 
hooves us to preserve them. 
Picking the teeth with a hard 
instrument, as a knife, fork or 
pin, or biting a hard object, as 
a nut, should be strictly avoid¬ 
ed ; for the enamel is not one 
solid piece, but thousands of 
six-sided prisms set close to¬ 
gether, like the brickte in a 
pavement. These are shown in 
surface view at E, Fig. 110. If 
some of these prisms are broken 
out, others will soon follow. 
Extremely hot or cold food 
should likewise be avoided. 

A tooth consists largely, of 
limestone. Review the experi¬ 
ments with acid and limestone, 
page 151. Strong acids decay 
the teeth quickly and weak 
acids will do so in time. Now, 
in the mouth there are many bacteria that produce acids out of 
food substances left there from the meals. The teeth should, 
therefore, be kept scrupulously clean, that is, free from food 
particles. Gentle brushing of the teeth after v each meal is 
the only safe rule to follow. Without food to live on the 



Fig-. 110.—Section of a tooth, show¬ 
ing its parts. E, surface view of 
the enamel, highly magnified. 







Where Digestion is Begun*. The Mouth. 


161 


bacteria could not exist in the mouth. Pretty teeth in a 
smiling mouth are also pleasant to look upon. 

Any injury to the teeth or decay should be repaired promptly. 
If possible, a damaged tooth should be saved. The upper and 
the lower set of teeth fit nicely upon one another. When a 
tooth is pulled, the gap causes the other teeth to change their 
position in the jaw so that the two sets of teeth no longer fit 
as before. Misshapen teeth should be straightened, for this 
increases their efficiency and improves one’s personal appear¬ 
ance 


Summary. 

The teeth are so important as organs of digestion that 
everything should be done to preserve them. Brushing the 
teeth to remove particles of food prevents the growth of acid- 
forming bacteria and thus helps to prevent decay. All defects 
of the teeth should be corrected promptly by a dentist. 

Questions. 


1. Name and locate the digestive organs. 2. Mention the parts 
that can be seen by looking into the open mouth. 3. Describe the 
digestion in the mouth. 4. What are the uses of the tongue? 5. Lo¬ 
cate the salivary glands and tell where the duct of each opens into 
the mouth. 6. Point out the different kinds of teeth in your mouth 
(compare Figs. 108 and 109). 7. Describe the structure of a tooth 

from an outline figure placed on the blackboard. 8. Why will acids 
dissolve the teeth? 9. How do bacteria cause decay of the teeth? 
10. Give reasons why the teeth should be preserved. 11. State sev¬ 
eral rules of hygiene regarding the teeth. 


CHAPTER XXIV. 


Digestive Organs Continued — Gullet, Stomach and 
Intestines . 


As the food is swallowed it passes through the pharynx or 
throat (Fig. 105) into the gullet or esophagus. This organ is 
nearly straight and leads directly to the stomach. The stom¬ 
ach has the greatest diameter of all parts of the alimentary 
canal, and its walls are thickest. Joining the stomach at its 



Fig - . 111.—A, a spool; B, half of a spool cut longitudinally; C, manner of 
cutting; spool to g;et D and E; D, a longitudinal section; E, a cross sec¬ 
tion. 


lower end is the small intestine. This is by far the longest 
part of the canal, measuring from twenty to thirty feet in 
length, which necessitates its being coiled up in the abdominal 
cavity. The small intestine joins the large intestine in such 
a way as to leave a “blind sac” (13, Fig. 105). To this is 
attached the “vermiform appendix,” (14), a useless organ. 






















Gullet, Stomach and Intestines. 


163 


When this becomes diseased the patient is said to have appen¬ 
dicitis* 

The Alimentary Canal a Hollow Tube.— Thus from the 
throat on the alimentary canal is a hollow tube, very much 
the same in all parts. All of the organs, gullet, stomach and 
intestines, are made up of the same kinds of tissues. This 
can be studied in cross sections and longitudinal sections. (See 
Fig. Ill for meaning of these terms). Fig. 114 represents a 
stomach and adjoining parts of the gullet and small intes¬ 
tine, with portions of each cut away so as to show the struc¬ 
ture. 

The gullet is not very likely to become injured or diseased. 
The commonest disease of the gullet is scarring from concen¬ 
trated lye swallowed by mistake. The scars contract and make 
the gullet so narrow that not even water can trickle through. 

The walls of the alimentary canal are made up largely of 
muscle, an outer layer running lengthwise and a thicker inner 
layer running in rings around the canal. It is by the action 
of these muscles, especially of the circular or ring muscles 
(1, 2 and 3, Figs. 113-115) that the food is forced along the 


♦Appendicitis begins with redness and swelling of the appendix. 
The swelling of the walls of the appendix may plug up the hollow 
space inside. If this plugging-up occurs near the end of the ap¬ 
pendix that leads into the large intestine, a lake is formed in the 
appendix which has no outlet. Pus germs, growing in this closed 
space, form gas, which stretches the appendix and may burst It. 
If the appendix bursts or ulcerates through, the pus germs inside 
flow out into the abdominal cavity and the inflammation may spread, 
causing peritonitis (page 166). A large proportion of all pain low 
down in the right side is due to appendicitis. A physician should 
be called promptly in these cases. 



164 


The Human Body and Its Enemies. 


canal. These muscles successively contract behind the food, 
so that a wave-like motion passes along the canal. This can 
be seen by observing the throat of a horse drinking water in a 
creek. The waves running along the neck of the horse (Fig. 
112) indicate the passage of each swallow of water up the 
gullet. This motion is called peristalsis, 
and occurs all along the alimentary canal. 
In the stomach the muscle fibers run also 
diagonally, allowing more varied motion, 
the “churning” of the stomach. 

Where the stomach connects with the 
small intestine the ring muscle is unusu¬ 
ally thick. When this contracts it closes 
the opening so as to keep the food in the 
stomach, just as a lady’s handbag is 
closed by pulling the strings. When the 
muscle relaxes the food may pass from the stomach into the 
intestine. This muscle, then, acts like a valve. It is called 
the pylorus (Fig. 114), or “gate-keeper,” of the stomach. Its 
action may be further illustrated by puckering up the mouth 
as in the act of whistling, for there is just such a muscle* 
around the mouth. 

Besides the thick circular layer the alimentary canal has a 
layer of epithelial tissue as a lining and one as a covering. 
The lining is called mucous membrane. It is only one cell 
thick (A, Figs. 120 and 121) in the stomach and the intestine, 
but much thicker in the mouth and the gullet. It is red from the 
presence of much blood so close to the surface. The covering 
(1, Fig. 114) of the stomach and the intestines is called the 



Fig:. 112. Ring mus¬ 
cles carry swallows 
of water up the 
horse’s throat. 


♦Such ring muscles controlling openings are called sphincter 
muscles. 






Gullet, Stomach and Intestines. 


165 



Fig. 113. A portion of the wall of the stomach, much enlarged; 1, perito¬ 
neum; 2 and 3, muscle layers; 4, lining of stomach; 5, openings of glands. 

Fig. 114. Gullet, stomach and small intestine, partly opened. Numbers 
same as in Fig. 113. 

Fig. 115. A portion of the wall of the small intestine, more enlarged than 
Fig. 113; 6, villus containing blood capillaries; 7, villus containing lymph 
capillaries; other numbers as in Fig. 113. 


































166 


The Human Body and Its Enemies. 


peritoneum; this also covers the inner walls of the whole ab¬ 
dominal cavity. Its work is to keep the surface moist so as 
to prevent friction when these organs rub against one another. 

Other Structures in the Stomach and the Small Intestine.— 

The gullet has a very simple structure, its function being 
merely to carry food to the stomach from the mouth and 
throat. It possesses the muscle layers and a smooth lining and 
covering. 

The stomach churns and mixes the food and passes it on to 
the small intestine. But it does more than this; it adds to the 
food a fluid to help in digestion. In the walls of the stomach 
are pockets or pits, as shown in Fig. 113, called gastric glands. 
These manufacture the digestive fluid called gastric juice. In 
the small intestine are similar glands extending back into the 
walls; these are the intestinal glands, producing intestinal 
juice. They correspond in structure to the gastric glands of 
the stomach. But in addition to these depressions in the small 
intestine there are finger-like outpushings of the mucous mem¬ 
brane called villi (singular villus). That is, whereas the glands 
lead down from the surface into the wall, the villi reach out into 
the hollow of the intestine. Carefully study Figs. 114 and 115 
in this connection. The large intestine does not have villi. 

The stomach and the intestine are also more folded or 
wrinkled on the inner surface than the gullet (Fig. 114). 
These folds serve to increase the surface and thus give more 
room for glands or for glands and villi. 

There are, then, very many tiny glands in the wall of the 
stomach and numerous similar glands in the walls of the 
small intestine. But all of these are not sufficient to produce 
enough juice to digest all of the food. Behind and below 
the stomach is a long finger-like gland, the pancreas, that pro¬ 
duces pancreatic juice, the most important digestive juice. 


Gullet, Stomach and Intestines. 


167 


The juice from this gland is gathered into a tube, the pan 


creatic duct, that leads to 
the intestine, as shown in 
Fig. 116. Just before enter¬ 
ing the intestine the pancre¬ 
atic duct joins a duct (the 
bile duct) which carries bile 
from the liver. Bile is a juice 
produced in the liver; it can 
be stored when not needed 
at once, in a bag, the gall¬ 
bladder (Fig. 116). 

Summary and review of 
the chemical action of the 
digestive juices to show 
what juices digest the various 



Fig 116. Some of the important di 
gestive organs of the abdomen. 


foodstuffs and where : 


Juice. 

Produced in 

Emptied Into. 

Digests. 

Saliva. 

Salivary Glands. 

Mouth. 

•••Starch. 

•Gastric. 

Gastric Glands. 

Stomach. 

•••Proteids. 

Intestinal. 

Intestinal Glands 

Small Intestines. 

Cane Sugar. 

1 ***Starch. 

J ***p ro teids. 
f •••Fats. 

Pancreatic. 

Pancreas. 

Small Intestines. 

••Bile. 

Liver. 

Small Intestines. 

None. 


♦Gastric juice also contains an acid (hydrochloric acid) which 
helps to destroy germs that get into the stomach. The acid also 
aids in digestion. Gastric juice will also curdle milk. 

**Bile is not strictly a digestive juice; but it furnishes condi¬ 
tions favorable for the other juices to act, and so indirectly aids 
in digestion. 

***See Chapter XXII for digestion of starch, proteids and fats. 













168 


The Human Body and Its Enemies. 


Summary. 

The alimentary canal is a long tube beginning at the mouth 
and including the throat, the gullet, the stomach and the small 
and the large intestines. The tube is lined with mucous mem¬ 
brane and covered with a thin tissue kept moist and smooth 
so as to reduce friction. The wall of the canal is made mainly 
of muscles to mix the food with the juices and to move it 
along. In the walls of the stomach and the intestine are many 
glands; other glands (salivary, pancreas and liver) are outside 
the canal but pour, their juices into it through ducts. 

The small intestine is the most important organ for chem¬ 
ical digestion. It is the only organ in which sugar and fats 
are digested, and in it the digestion of the proteids and starch 
is completed. Where is the digestion of proteid begun? Of 
starch ? 


Questions. 


1. Mention the parts of the alimentary canal numbered in Fig. 
105. 2. With a spool before you, draw a cross section and a longi¬ 

tudinal section of a spool. 3. Do the same for a top. 4. Sketch 
cross sections of the gullet, the stomach and the small intestine. 
5. What is the use of the muscle layers of the alimentary canal? 6. 
How is this use illustrated in Fig. 112? 7. Describe the pylorus. 

8. Draw a longitudinal section through the pylorus (Fig. 114). 9. 

Where is the mucous membrane found? 10. The peritoneum? 11. 
Locate the gastric glands. 12. With page 156 before you, compare 
these glands with the intestinal glands. 13. Where are the villi found? 
14. From what part of Fig. 114 is Fig. 113 supposed to be taken? 
Fig. 115? 15. In what organs is starch acted on? Proteids? 16. 

What is the only juice that can digest fats? 17. What foods are di¬ 
gested in the intestine? 18. Where is the chemical digestion of 
proteids begun? Of starch? Of fats? Of cane sugar? 


CHAPTER XXV. 


The Digestive Glands. 

Definition of a Gland. —You know by this time at least what 
a gland does; that is, it produces or “secretes” a fluid or a 
juice. You can make a list of at least four digestive juices 
and tell by what glands they are secreted. The mouth is 
always moist because the salivary glands secrete saliva and 
pour it into the mouth. There are many different kinds of 
glands in the body besides those already mentioned. The 
tear glands might be mentioned. They keep the eyes moist, 
and when you cry the eyes run over with the fluid from the 
tear glands. 

How the Gland Cells Are Arranged. —Let us point out the 
kinds of cells that glands are composed of and how these cells 
are arranged. Gland cells are epithelial (E, Fig. 117), that is, 
they are arranged side by side so as to make a layer, as shown 
in the diagrams in the figure. This layer has one surface lying 
against the connective tissue, in which there is a rich supply 
of blood vessels. Where these come close to the gland cells 
they are thin-walled so that the substances may readily be 
taken out of the blood by the cells. These substances are 
changed into juices which ooze through the cells and are given 
off on the free side of the epithelial layer. Diagram 1 of Fig. 
117 represents the glandular layer as flat. An example of 
such a layer is the peritoneum (1, Fig. 114), already referred 
to as secreting a lubricant for the abdominal organs. A gland 
of this kind, if extended, takes up a great deal of space, there¬ 
fore, most glands have the secreting surface pushed down into 


170 


The Human Body and Its Enemies. 


pockets and tubes as figured in longitudinal sections in dia¬ 
grams 3-7, Fig. 117. Blood vessels surround these glands and 
come close to the gland cells; the hollow of the gland serves 
to catch the secreted fluid and to give it off at the opening, 
the mouth of the gland (M). The relation of blood vessels and 
gland cells is again shown in Fig. 118. Just such glands are 



Fig. 117.—Diagrams of various types of glands. E, epithelial layer made 
up of the gland cells; B, blood capillaries; M, mouth of gland; D, duct. 
1, gland with flat epithelial layer; 2 and 3, pocket-shaped glands; 4 and 
5, tuoular glands, the one at 5 having tube so long as to necessitate its 
being coiled up at the lower end; 6, gland with blood vessels coiled up 
inside of epithelial layer; 7, compound gland with many pockets and ducts. 


found in the walls of the stomach and the intestine. They 
may be simple, as shown in Fig. 118, or compound, that is, 
with several branches, as in diagram 4, Fig. 117. Their exact 
position is seen in Fig. 114, where the wall of the stomach is 
represented as cut away, exposing a section of the wall. These 
glands are very small, much smaller than shown in Fig. 114, 
which has the stomach about one-fourth natural size, but shows 
























The Digestive Glands. 


171 


the glands enlarged five or more times. Fig. 113 represents a 
block of the stomach wall more enlarged; it shows how nu¬ 
merous are the gastric glands in the stomach. 


The intestinal glands are similar, usually simple, like the 
gastric gland, shown in Fig. 118. Study them also in Fig. 115. 
Among the glands are projections, the villi, which project out 
from the walls while the glands 
extend down into them. The duty 
of the villi we shall study below. 

Other Glands. —The glands just- 
described occupy all of the space 
possible in the stomach and the 
intestine, but as they are not suf¬ 
ficient to supply the alimentary 
canal with all of the digestive 
juices needed, there are other 
glands of large size outside the 
canal but communicating with it 
by ducts or tubes to carry the 
juice from the gland to the proper 
organ. As already noted, these 
glands are: six salivary glands 
emptying their secretion into the 
mouth, the liver and the pancreas 
both opening into the small intes¬ 
tine. The three salivary glands on the left side are named and 
located in Fig. 107, which also shows the ducts and their place 
of opening into the mouth. The largest pair, the parotid, 
situated below and in front of the ear, becomes swollen when 
one has the mumps. 

Describe the location of the pancreas; of the liver. The 
liver, salivary glands and pancreas are very complex organs, 



AE.IN 


Fig. 118.—A gastric gland from 
Fig. 113, highly magnified. GL, 
gland cells; M, mouths of 
other glands. 









172 


The Human Body and Its Enemies. 


not simple glands, as are the gastric glands, for example. 
These may have several branches at most; but glands like the 
pancreas have many branches and parts, as indicated in Fig. 
119. Here it is seen that the gland really consists of many 
parts or pockets, each one of which is like a gastric or an 
intestinal gland. Compare 8 and B, Fig. 119, with Fig. 118. 

From the part 8, 
Fig. 119, the juice 
is poured into 
tiny ducts, and 
from these into 
larger and larger 
ones (1, Fig. 119), 
and finally by a 
large duct (Fig. 
116) into the in¬ 
testine. B and C 
(Fig. 119) show 
the working cells 
of the gland, and 
it is readily seen that these are epithelial cells (compare with 
Fig. 117. After the manner of all glands they get material 
from the blood (BY) wherewith to make their secretion. 



a number of pockets that empty their juice into 
duct (partly cut open); 8, a pocket in longitudi¬ 
nal section, more highly magnified at B; 
3, a pocket in section, more hig-hly magnified 
at C; 4, small duct; BV, blood vessel; 5, appear¬ 
ance of gland cells before a meal; 7, after a 
meal. 


Summary. 

There are many different kinds of glands in the body, 
but they all agree in having the cells that do the work ar¬ 
ranged as an epithelial tissue which lies upon connective tissue 
very rich in blood. The cells secrete fluids, that is, take 
out of the blood materials and make them over into various 
fluids. The digestive glands are of five kinds: (1) the gas- 



The Digestive Glands. 


173 


trie glands in the walls of the stomach; (2) the intestinal 
glands in the walls of the intestine—these are very simple and 
numerous. Outside the alimentary canal, but communicating 
with it, are: (3) six salivary glands, (4) the pancreas and (5) 
the liver. 


Questions. 


1. What kind of tissue contains the working cells of a gland? 
2. What letter marks the layer of gland cells in Fig. 117? 3. Where 

do the cells get the material from which to make their juices? 4. 
Which gland can secrete the more juice: C or D of Fig. 117? 5. 

Which has more gland cells? 6. Describe a gastric gland. 7. Where 
are glands like this shown in Fig. 113? 8. Locate them also in 
Fig. 114. 9. Compare the glands of Fig. 115 with the gastric 
glands. 10. What part of Fig. 119 is like a gastric gland? 11. 
Why does the blood have to come near the working cells of a 
gland? 12. Where are the gland cells of Fig. 118? Of Fig. 119? 


CHAPTER XXYI. 


How the Food Is Taken Up by the Blood: Absorption 


Digestion has been defined as the process of making the 
insoluble food soluble. Even after this has been accomplished, 
if the food remains within the alimentary canal, it does the 
body absolutely no good What use can it be to the cells 
of hand or head or foot? To be of use to any part of the 
body it must be carried to that part. How is it carried 
from the food canal to all parts of the body? You will at 
once answer, by the blood. The blood is the carrying agent 
of the body. Bear this clearly in mind: the blood carries 
food to the cells and waste matter away from them. What 
we have to consider now is how the food gets into the blood, 
or, in other words, how the blood absorbs the food. 

Where the Food Is Absorbed. —What foodstuffs are absorbed 
from the stomach; that is, what foodstuffs have been partly 
digested in the mouth or the stomach? In the intestine diges¬ 
tion of all foods is completed. 

Fig. *120 represents a small part of the wall of the stom¬ 
ach, highly magnified, several glands being shown. What 
is the work of the cells at B? What is the function of the 
blood vessels running to these cells? What is the function 
of the cells at A? These cells at A, it is to be noted, touch 
the food inside the stomach. These are absorptive cells,'taking 
up salts and digested starch and proteids and passing them on 
to the blood vessels just underneath them. Compare with 
Figs. 113 and 118. 

When we look at the inner surface of the small intestine we 


How the Food Is Taken Up by the Blood. 175 

find it like the stomach in that it is in folds, but it differs in 
its soft, velvety appearance. If somewhat enlarged, the vel¬ 
vety surface comes to look more like the rough surface of a 
good coarse bath towel. This is due to the presence of tiny 
projections, the villi. Between the villi are the intestinal 
glands. Fig. 115 
shows glands and 
villi in surface 
view and in sec¬ 
tion. 

The function of 
the villi is to ab¬ 
sorb the digested 
food. This will be 
better understood 
from a study of 
Fig. 121. The villi 
are represented in 
section at 1, and 
the glands at 2. 

What is the func¬ 
tion of the cells at A? of those at B? What advantage has 
the small intestine over the stomach in the way of absorb¬ 
ing food? Note that the cells at B of these figures take sub¬ 
stances out of the blood (gland cells), while those at A pass 
food substances into the blood. Since most of the food is di¬ 
gested in the intestine it is also here largely absorbed. This 
requires a very large surface. There are three ways by which 
the surface of the small intestine is increased: (±) by the 
great length of the intestine; (2) by the folds of the inner 
layers (Fig. 114) ; (3) by the villi, as just discussed. The 
folds are covered with innumerable villi. 


FIG. 120. FIG 121. 



Fig:. 120.—Diagram of portion of wall of stomach, 
showing: three gastric glands; A, absorbing cells; 
B, gland cells. 

Fig. 121.—Diagram of portion of wall of intestine, 
showing a villus (1) and three intestinal glands 
(2). Other features as in Fig. 120. 


















176 


The Human Body and Its Enemies. 


The villi are important absorptive organs. Fig. 122 is a dia¬ 
gram showing three villi. Note the mucous membrane cover¬ 
ing. (M). It is through this that the food must pass. Ready to 
receive the food that passes in are (1) blood capillaries (fine 
blood vessels), and (2) lymph capillaries, called lacteals. These 
divide the work of carrying off the food: the blood capillaries 

take up the digested 
proteids and carbohy¬ 
drates, and the lacteals, 
the fats. All blood and 
lymph finally reach the 
heart, but by different 
routes. The carbohy¬ 
drates and proteids 
pass by the portal vein 
to the liver and thence 
to the large vein run¬ 
ning into the heart 
from below; the fats 
pass through the lymph 
glands, thence by the 
great thoracic duct in¬ 
to a large vein running 
towards the heart from 
above. (See Fig. 
124.) 

Osmosis.—Consult Fig. 121 again. Note that the food 
must pass through a membrane to get into the blood; also 
through the walls of the blood vessels. We say it does this by 
osmosis, by which we mean that it oozes or soaks through a 
thin, moist membrane. Some substances pass through a mem¬ 
brane easily, as, for instance, water or salt solution. Other 


a. b. c. 



Fig-. 122.—Three villi of the intestine: A. 
with blood capillaries (c) and lacteal (1); 
B, with blood capillaries only; C, with 
lacteal (1) only; g-, intestinal gland. 






















How the Food Is Taken Up by the Blood. 


177 


substances, like gelatine or the white of an egg, do not osmose 
to any extent. These must therefore be digested before they 
can be absorbed into the blood by the process of osmosis. 

Experiment to Illustrate Osmosis.—Take 
an egg, a glass tube or a straw about a foot 
long, a bottle to hold the egg and a vessel to 
hold the bottle and the egg, as shown in the 
accompanying figure. With great care crack 
the shell at the large end of the egg. 
and pick off the bits of shell with the finger¬ 
nail, being careful not to injure the mem- 

Now, punch a hole 
in the other end of 
the egg, and into 
this stick a straw 
as far as the center 
of the yolk of the 
egg. With melted 
beeswax or paraffin 
or tallow seal the 
joint of the straw to 
the egg. Set up the 
apparatus, as in Fig. 

123, and add water, immersing half of the 
egg, and await results. ' If the membrane 
of the egg is not broken where it touches 
the water, the water will pass into the 
egg faster than the contents of the egg 
will pass out. This causes the contents 
of the egg to rise in the tube. Watch 
the experiment and explain what you see. 


Summary. 

After the food is digested it is 
worthless unless absorbed by the blood 


brane under the shell. 



Fig:. 124.—Diagram to 

show the course of 
foodstuffs to the heart. 



Fig. 123.—Experiment 
in osmosis. B, bot¬ 
tle; .T, jar; both con¬ 
taining water; E, 
egg; T, glass tube 
or straw sealed to 
egg with wax (W). 













178 


The Human Body and Its Enemies. 


and carried to the hungry cells of the body. The digested 
or liquid food is absorbed through the thin mucous 
membrane of the stomach and the small intestine, especially 
of the latter; for, projecting out of the wall of the small in¬ 
testine, are thousands of villi containing blood and lymph ca¬ 
pillaries that take up the food and carry it by the veins to 
the pumping station, the heart. 

Questions. 

1. Why must food get into the blood? 2. How does the food 
pass in? 3. Why must food be soluble to be absorbed by the blood? 
4. What membranes must the food pass through to get into the 
blood? (Fig. 120 and 121.) 5. Describe an experiment to illustrate 
osmosis. 6. Describe a villus. 7. What membrane in Fig. 121 cor¬ 
responds to the membrane around the egg in Fig. 123? 8. What 

organ in a villus takes up fats? 9. Proteids and carbohydrates? 
10. What foodstuffs pass through the liver before going to the 
heart? 11. What cells in Fig. 121 are touched by the nearly 
liquid contents of the intestine? 


CHAPTER XXVII. 


The Making of Living Substance: Assimilation. 

We have thus discussed in the last few chapters: (1) kinds 
of food that are eaten; (2) how these foods are digested, or 
prepared for absorption; (3) how they are absorbed or taken 
into the blood to be pumped by the heart to all of the cells 
of the body. We will now consider how the food passes out 
of the blood to supply the cells of the body. 

Blood as the Carrier. —It may be said that the food gets out 
of the blood after it has reached the hungry working cells in 
a distant part of the body in the same way as it gets in at the 
villi—by osmosis. The blood absorbs food through the cells 
covering the villi. For this purpose the blood capillaries come 
close under the mucous membrane cells covering the villi (Fig. 
122), through which the food is absorbed. By osmosis the 
food enters the blood. Let us now see that the blood capilla¬ 
ries pass the food on to the other working cells of the body, 
just as the cells of the villi pass it on to the capillaries. Fig. 
125 shows the blood tubes or vessels lying close to the cells 
of the body. These might represent any cells, as of the head, 
foot or finger. The blood vessels leading toward the cells of 
an organ of the body are called arteries ; they branch and grow 
smaller and smaller the further they are from the heart. After 
they have become very small and thin-walled, they are called 
capillaries. Through these capillaries the blood flows into 
veins, which carry the blood back to the heart to start over 
again on its round or circulation. As the blood passes through 


180 


The Human Body and Its Enemies. 


the capillaries it comes close to the cells of the body. Note 
that it does not touch the cells, but stays in the blood vessels— 
it merely passes close enough to the cells so that, by osmosis, 
the food may pass to the cells, just as water passes into the 
egg through the egg membrane in the experiment described 
above. Fig. 125 also shows another condition that deserves 
special notice: the cells of the body are surrounded by a thin, 
colorless fluid called lymph. It may be said that we, that is our 

cells, live in a fluid just as fish live 
in water. You will note by studying 
the diagram that substances which 
pass from the blood to the cells 
must first pass through the lymph 
that fills all of the spaces among 
the cells. 

Assimilation. —The question now 
is: What becomes of the food after 
it reaches the cell? This is the cli¬ 
max of the subject—the food be¬ 
comes in part living substance. This 
is called assimilation (Latin ad, to 
and similis, like). Only living sub¬ 
stance is able to do this—to make 
dead matter over into living matter like itself. This living 
matter, found in all living cells, is called protoplasm. A cell 
has therefore been defined as a mass of protoplasm, containing 
a nucleus (Fig. 83). In doing work a cell uses up some of its 
protoplasm, but it creates new protoplasm out of food brought 
to it— it repairs itself. No machine can do this as can the 
living body. 

Growth of Cells. —It is easy to see from this how cells grow 
and multiply. As the body grows more cells are developed 



Fig. 125.—Diagram to illus¬ 
trate the relation of cells, 
lymph and blood. CO — 
carbon dioxide. 


The Making of Living Substance: Assimilation. 181 

from those already there. The cell grows until it becomes 
“full size,” when it splits in two (Fig. 126) ; then there are 
two cells to grow again to full size and to multiply as before. 
When the skin is injured it grows back from around the edge 
of the wound, for the skin is formed only from skin cells al¬ 
ready present. The material for growth is furnished by the 
blood under and in the skin. Assimilation, growth and mul¬ 
tiplication are processes that are performed only by proto¬ 
plasm or living substance contained in the cells of animals 
and plants. 

Wastes.— In burning or oxidizing the tissues and food in 

the body, waste 
subs t a nces are 



produced by the 
cell. The chief 
waste substances* 
are carbon diox 
ide and uric 


Fig. 126.—Cell growth and division. 


waste. These are harmful to the cells and must be carried 
away by the blood. So without end, from birth till death, 
protoplasm is built up out of food and torn down by oxida¬ 
tion (burned) that life may go on. It is truly “life by death.” 

Food Storage. —But some substances can be stored in the 
body, to be used in case of need, when food cannot be eaten 
or secured. How long can a person live without eating? A 
kind of starch (liver starch) is prepared by the liver and 
stored in the liver and muscles. Other foodstuffs are made 


♦Here are not included the indigestible wastes passed from the 
small intestine into the large intestine. These wastes are not pro¬ 
duced by the cells of the body, never having been absorbed by 
the villi. 



182 


The Human Body and Its Enemies. 


into fat by the cells of the body and stored in certain cells. 
These cells grow larger and larger until filled with large drops 
of fat, as shown in Fig. 127. 



Fig-. 127.—Growth of a fat cell by the accumulation of drops of oil. 


How Disease Germs Feed in the Body. —Sometimes some of 
the food that is digested in the alimentary canal and made 
ready for absorption goes to support foreign plants and ani¬ 
mals called parasites, that get into the blood accidentally. 
Such a parasite is the tapeworm, which lives in the intestine. 
It has no eyes, limbs, mouth or digestive organ of any kind— 
it simply lies in the food substance in the intestine and soaks 
up the food through the walls of its body by osmosis, just as 
a cell of the body does. The person or animal in which the 
tapeworm lives does the work of digestion for it. Besides 
large parasites like tapeworms, hookworms, etc., there are mil¬ 
lions of disease germs that sometimes live in the body. These 
and their harmful effects have already been described. 

A moment’s reflection will show you why it is that para¬ 
sites often thrive in our bodies. There are three things living 
beings need in order to live: food, water and oxygen. In 
the body parasites find these things: (1) food in the mouth, 
mucous membrane, the stomach and intestine, the blood and 
the cells; (2) water, for seventy-five per cent of the body 
is water; (3) oxygen is constantly being carried from 
the lungs to the tissues. Most parasites also need warmth 
and this we also furnish, for our bodies are always at a uni- 


The Making op Living Substance: Assimilation. 183 


form temperature of 98.6 degrees Fahrenheit. No wonder 
that many kinds of bacteria and cither parasites make our 
bodies their home, for we take so good care of them. 

This can be made plain by Fig. 

128. Suppose we take a bacte¬ 
rium living in the blood. From 
the blood it takes food and oxy¬ 
gen and water, and into the blood 
it pours its waste substances. 

With the waste substance it gives 
off poisons called toxins (page 5), 
which cause disease by destroying 
our own cells. Then our cells go 
to work producing antitoxin (Fig. 

128) to destroy the toxin, thus 

often protecting us against the Fjg m _ Diagram to show 

harmful effects of disease '^bfood.^kinf™ food'US 
germs. oxygen (O) and giving off 

wastes and toxins. 



Summary. 

The most wonderful substance in the world is proto¬ 
plasm, the living substance of which the cells of our bodies 
are composed. The most wonderful thing this protoplasm can 
do is to change the food we eat into substance like itself. 
This process is called assimilation. The cells of the body 
are surrounded by lymph. Food passes by osmosis out of 
the blood capillaries into the lymph and then into the cells, 
and waste matter passes back into the blood. Disease 
germs feed in the body just as the cells of the body them¬ 
selves do. 




184 


The Human Body and Its Enemies. 


Questions. 


1. What is the chief work of the blood? 2. Define arteries, ca¬ 
pillaries and veins. 3. In which of these does the blood take on and 
give off its loads? 4. Why do the capillary walls have to be thin? 
5. Does the blood touch all of the cells of the body? 6. What is the 
use of lymph and where is it found? 7. What is assimilation? 8. 
What is the most wonderful work of protoplasm? 9. Where is 
protoplasm found? 10. How are waste substances produced? 11. 
What are the chief wastes made by protoplasm? 12. Why do the 
cells have to tear down after building up? 13. How do wastes get 
into the blood? 14. What does the blood do with them? 15. Draw 
Fig. 125 on the board and discuss the work of cells. 16. Show how 
disease germs feed in the body just as the body’s own cells do. 17. 
How do germs harm the body? 18. What is produced by the cells 
of the body to counteract the germs of disease? 


CHAPTER XXYIII. 

Why We Breathe. 

Review. —In the previous chapters it was pointed out that 
the cells of the body are continuously in need of food and 
that this food is needed by the cells for growth and repair, 
and to keep them warm and to enable them to work. It was 
also shown that it is not the food itself that produces heat, 
but the burning of the food, or the burning of cell substance 
itself, that causes us to be warm and enables us to move. We 
might compare the body to a stove. The stove is not heated 
merely by laying the wood into it, but by the burning of the 
wood. To burn the wood, a draft into the stove is necessary; 
cut off the draft and the fire goes out. This simply means 
that oxygen from the air is needed to combine with the wood 
to produce heat. The same is true of the body. What the 
draft is to the stove the breath is to the body. Oxygen is 
needed by the cells to burn up the food and to keep up the ac¬ 
tivities of life; stop breathing, and the body dies and grows 
cold. 

In the present chapter we shall see how the cold, dust-laden 
air containing the oxygen we need, becomes warmed and 
cleaned as it passes through the nose, the voice-box and the 
wind pipe into the lungs; how, after reaching the lungs, the 
oxygen gets very close to the blood, and how it is absorbed 
by the blood so as to be carried where it can be of use to the 
cells of the body. 

How Carbon Dioxide (CO.) Is Produced. —You have 
learned that plants, in the making of starch, used up the C0 2 
from the air and gave off oxygen into it, thus purifying the air 


186 


The Human Body and Its Enemies. 


for men and animals. You learned, too, that starch and other 
foodstuffs contain carbon, and that when burned in the body 
the carbon combines with the oxygen to form C0 2 . This is 
waste matter and must be given off by the cells into the lymph 
and blood, and carried away to 
be thrown off from the body in 
the breath, just as the waste pro¬ 
ducts from burning of w T ood in 
the stove or furnace are given off 
into the stovepipe or chimney as 
smoke and gas. 

Respiration Defined. —This pro¬ 
cess of taking up oxygen and giv¬ 
ing off C0 2 is called respiration; 
or, in other words, respiration is 
the exchange of C0 2 for oxygen. 

Every cell does this (see Fig. 

129); therefore every cell re¬ 
spires. But the cells are so far from the outside world, that 
the blood must carry oxygen to the cells and C0 2 away from 
them. In the earthworm the exchange of gases between the 
blood and the outside air takes place through the whole skin. 
In the fish the gills are the organs of respiration. The gills are 
covered with a thin membrane and filled with blood; it is 
through this membrane that the fish takes oxygen out of the 
water and gives off C0 2 into the water. In man and the higher 
land animals the air containing oxygen must be taken into the 
lungs (inspiration) and breathed out again (expiration). While 
in the lungs the air gives off oxygen to the blood and takes 
C0 2 from it. Just how the thin membrane through which 
the exchange of gases takes place acts, and how the blood 
comes close to this thin membrane, we shall see below. 



Fig-. 129.—Diagram illustrating 
respiration of the cell of the 
body. CO —carbon dioxide. 




Why We Breathe. 

Observation and Experiments.— (1) Bring 
earthworms to school and place them in shal¬ 
low dishes or plates with a little water. Earth¬ 
worms must be kept moist, for if their skin dries 
they cannot breathe through it, and therefore 
they die. Note the red blood vessels through 
the skin of the animal. Why is it that fish and 
men cannot have skin delicate enough for oxy¬ 
gen to pass through? (2) Keep a goldfish, min¬ 
now or other fish in a clear glass jar of wa¬ 
ter. Where are the fish’s gills? Note that the 
water goes into the mouth and out of the gills- 
slits on the side just behind the head. Hoys 
who have “strung” fish can tell all about 
this. How does the fish take up oxygen 
dissolved in water and give off CO s into the water? (3) Watch 
your deskmate breathe; that is, inspire and expire air. Watch 

him when he is not aware of it and 
count the number of breathing move¬ 
ments per minute. (4) Take a short 
candle and light it. Invert a fruit jar 
over the candle and note what hap¬ 
pens (Fig. 130). Why does the can¬ 
dle go out? Air contains four parts 
of nitrogen to one part of oxygen. 
But not all of the oxygen can be 
burned out of the air with a candle, 
for the candle goes out before all of 
the oxygen is gone. (5) To show 
more plainly that some of the oxygen 
disappears, burn a match head under 
a quart jar, with the jar inverted 
over water, as shown in Fig. 131. To 
do this the match must stand upright 
and be surrounded by an inch of two of water in a broad vessel. The 
match can be stuck into a square block of potato to hold it up. 
Now, with another match light the match that is to burn out the 
oxygen from the jar. As soon as the match begins to burn, quickly 
place the jar over it and into the water. Watch the water rise in 



Fig. 131.—Burning the oxygen 
out of a jar (J) of air; M, 
match stuck into a piece of 
potato in a dish (D) of water. 
A, level of water after re¬ 
moval of oxygen by burning 
of match-head. 


187 



Fig. 130.—A candle 
will go out for 
lack of oxygen if 
covered with a 
jar. 







188 


The Human Body and Its Enemies. 


the jar. The oxygen has been used up out of the air in the jar, and 
the water has taken its place (Fig. 131). (6) That expired air 

contains large amounts of CO^ can be demonstrated easily. Dis¬ 
solve a little fresh lime (such as masons use to make mortar) in 
some water and either filter it to get it clear, or allow it to stand 
covered until the undissolved particles settle to the bottom; then 
pour off the perfectly clear liquid on top. Now, with a straw or 
a glass tube blow your breath through this clear liquid (Fig. 132). 
The milky condition of the liquid indicates that C0 2 has been 
added to it. 

Summary. 

Respiration is the exchange of 
C0 2 for oxygen. The oxygen is 
taken from the air, and is used in 
the body for oxidation. The oxy¬ 
gen unites with the carbon of our 
food and tissues, producing C0 2 , 
a waste substance, injurious to 
the body. Every cell of the body 
uses oxygen and gives off C0 2 . 
The blood carries the oxygen to 
the cell and the C0 2 away from 
it. The C0 2 leaves the body in 

Fig.- 132.— clear lime-water will the breath, as can easily be seen 
become milky from carbon di- i 
oxide in expired air. Dy experiment. 

Questions. 

1. Define respiration. 2. How is CO o formed in the body? 3. 
In a stove? 4. Why is oxygen needed? 2 5. Why do we need more 
oxygen when running than when sitting? 6. What common obser¬ 
vation seems to prove this? 7. How does each cell secure oxygen 
and get rid of C0 2 (Figs. 125 and 129)? 8. How does the whole 
body get rid of C0 2 and take on oxygen? 9. How can you prove 
that about one-fifth of air is oxygen? 10. How can you show that 
C0 2 is given off in the breath? 





CHAPTER XXIX. 


The Breathing Organs. 


The breathing organs, or the organs of respiration, are the 
lungs, the air passages carrying 
the air to and from the lungs, the 
bones of the chest and the mus¬ 
cles attached to them. The chest 
and its muscles work together in 
the breathing movements. 

The air passages are the nasal 
passage leading from the nostrils 
back to the throat or pharynx, 
where the air passage and the 
food passage cross; the larynx, 
or voice box, the trachea, or wind 
pipe, the last named dividing op¬ 
posite the lungs into two bronchi, 
and these, after entering the 
lungs, divide into smaller and 
smaller bronchial tubes or bron¬ 
chioles, as the branches of a tree 
divide until the smallest twigs 
are reached. All of these are 
illustrated in the figures. 

The nasal passages, like the 
mouth and throat, and other organs before mentioned, are 
lined with mucous membrane. Here end the nerves of smell, 
which can detect odors in tiny particles coming in with the 



Figr. 133.—Diagram of the air 
passages; arrows show cross¬ 
ing of food and air passages 
in the throat. Air sacs of 
lungs and pleurae shown. 




190 


The Human Body and Its Enemies. 


air we breathe. We say the nose is the organ of smell. The 
mucous membrane is, furthermore, richly supplied with 

blood; and as the passage 
is very crooked because of 
passing between and around 
the irregular bones* (Fig. 134) 
of the skull, the air is warmed 
as it passes through. The nos¬ 
trils are beset with hairs so as 
to prevent coarse particles of 
dust from passing further into 
the air passage. Now, mention 
two reasons why we should 
breathe through the nose and 
not through the mouth. Very 
often 

grown persons) have spongy 
growths called adenoids just behind 
the nose (Fig. 135), thus stopping 
up this passage and forcing the pa¬ 
tient to breathe through the mouth. 

Children who are “mouth-breath¬ 
ers” are not healthy, and when they 
attend school do not do well in their 
studies. 

The larynx or voice box leads off 
from the pharynx. As the air crosses 
in the pharynx the path taken by the 
food (see Fig. 133) there is danger 
of food as well as air going down into the larynx. To prevent 


children (and rarely 



Fig. 135.—Ad enoids are 
spongy growths in the nose 
that tend to stop up the 
nasal passages. (Compare 
with Fig. 133.) 


BASE OF BRAIN 



TURBINAL5 


PALATE 


TOOTH 


Fig. 134.—The turbinal bones, 

showing the irregular nasal pass- 




♦Called the turbinals, a pair of the skull bones. 




The Breathing Organs. 


191 


this there is a flap, the epiglottis (Pig. 139), that fits down 

over the top of the larynx during swallowing, and is raised 

during breathing. Point out this organ in Fig. 133. Can you 
raise and lower your epi¬ 
glottis at will? The larynx 
is a “box” of cartilage tis¬ 
sue (called gristle by butch¬ 
ers) which is strong and 
somewhat elastic. The “Ad¬ 
am’s apple” at your throat 

is the front of the larynx. 

Feel it and press it. Carti¬ 
lage tissue, shown in Fig. 

136, consists of cells with 
tough and elastic substance 
between the cells. It is an¬ 
other of the tissues of the 
body and finds a variety of uses. Name the other tissues you 
have studied. The larynx is made largely of cartilage so as 
to keep the passage always open for the air; for cartilage, 
while elastic, is stiff enough to support organs. The outer 
ears and the tip of the nose are supported by cartilage. Feel 
them. If the larynx were made of connective tissue instead 
of cartilage what would happen during inspiration? 

Experiments on the Voice.—Take a strip of paper about three- 
fourths of an inch wide and two inches long, or a blade of grass 
of that size and place it between the thumbs, as shown in Fig. 13 7. 
Now blow hard against the edge of the paper or grass. Stretched 
across the larynx are two flaps of connective tissue, each of which 
corresponds to the strip of paper you used in the experiment. (2) 



Fig. 136.—Cartilage -tissue. 


192 


The Human Body and Its Enemies. 



breath is blown upon a, a slip of 
paper between the thumbs. 


To prove that the vocal cords 
are located in the larynx, sing 
a note, and as you sing, alter¬ 
nately press against and let go 
of the Adam’s apple. When 
you whisper you do not use the 
vocal cordo. (3) As the vo¬ 
cal cords produce sound the 
hollow’s of the throat, mouth 
and nose increase the sound. 
To illustrate this, hold up a 
tin bucket horizontally to one 
side of the mouth and speak 
into the bucket, noting the ef¬ 
fect. 


The -structure of the trachea, bronchi and bronchioles is al¬ 
most the same. They are held open by rings of cartilage (A 
and B, Fig. 139), and are lined with mucous membrane, as is 
also the larynx. This mucous membrane has a peculiar struc¬ 
ture. The cells are supplied 
with tiny hair-like projec¬ 
tions called cilia (Fig. 138) 
standing out from the mem¬ 
brane into the tube. These 
cilia are constantly in mo¬ 
tion and act like living 
brushes sweeping mucus 
containing fine dust par-j 
tides out of the lungs to-j 
ward the throat, where itj 
gathers to be coughed up.| 

What two provisions has nature, then, made to keep dust 
out of the lungs? 

The Lungs. —Study Figs. 4 and 5 and the figures in this 



DVJ5T 

CILIA 


tLLS 


Fig-. 138.—Ciliated cells of the air 
passages have it as their duty to 
sweep dust back into the throat. 



















The Breathing Organs. 


193 


chapter. How many lungs are there ? What is their location 
with reference to the heart? How are they connected with the 
bronchi? In what cavity do they lie? What organ do they 
touch below? How are they and the heart protected from in¬ 
jury? 

The lungs are made up largely of air tubes, air spaces and 
connective tissue and blood vessels. The air spaces make them 
light and spongy, so 
that ' they expand 
and contract readily 
with each inspira¬ 
tion and expiration. 

In their movements 
the lungs rub against 
each other, against 
the diaphragm, 
against the heart and 
against the walls of 
the thorax. To re¬ 
duce friction they 
are covered with a 
double bag, two pleu¬ 
rae (singular pleu¬ 
ra), between the two 
layers of which is se¬ 
creted a liquid, the 
pleural fluid. One pleura thus covers the lungs, the other lines 
the thorax, as shown in Fig. 133. What is the function of the 
pleural fluid? When the pleurae become inflamed and hot, a 
person is said to be afflicted with pleurisy. Compare the 
pleurae with the peritoneum. 

How We Breathe. —We breathe by making the cavity of 



Fig-. 139.—The lungs and air passages (A); B, 
a small part of the trachea or windpipe, 
magnified, showing cilia and cartilac in the 
wall; air sacs in upper right hand corner are 
a portion of A enlarged; D, the tiniest air 
sacs still more enlarged. 



194 


The Human Body and Its Enemies. 


the chest alternately larger and smaller. When it is made 
larger there is more room for air and air comes in to fill the 

FIG. 140. FIG. 141. FIG. 142. 



Fig - . 140.—The chest and abdomen in inspiration. AB, horizontal diame¬ 
ter; CD, vertical diameter of chest; D, diaphragm. 

Fig. 141.—The chest and abdomen in expiration. 

Fig. 142.—Inspiration is partly due to the raising of the ribs. Solid lines, 
position of organs in expiration; dotted lines, in inspiration. Muscles 
between two of the ribs are shown at M. 


space. The question “How we breathe” becomes “How do 
we make the cavity of the chest larger or smaller?” A study 
of Figs. 140-142 will illustrate the two ways of increasing the 
capacity of the chest. Comparing Fig. 140 with Fig. 141 it 
will be seen that by lowering the diaphragm D the diameter 








The Breathing Organs. 


195 


C to D is increased; when it is raised, the space of the chest 
is decreased and air is forced out. The diaphragm is there¬ 
fore one of the breathing organs. It is a flat muscle and is low¬ 
ered by contraction. Measuring the diameter AB with a slip 
of paper in the two figures, it will be found to be greater in 
Fig. 140. This diameter is increased by raising the ribs. You 
will note that the ribs are inclined forward. At M, in Fig. 141, 
are shown muscles between two adjacent ribs. Such muscles 
exist between all of the ribs, .and when they contract the ven¬ 
tral ends of the ribs are raised and the chest expands. The ribs 
and the muscles between them are also breathing organs. 
When the size of the chest cavity is thus increased, air rushes 
in because of the greater pressure from without, and the lungs 
thus expand. When the ribs fall or are pulled back, air is 
forced out of the lungs. Fig. 142 indicates the relative posi¬ 
tions of thoracic and abdominal walls at inspiration (dotted 
lines), and at expiration (solid lines). The harmful effects of 
tight clothing about the waist or chest are readily understood 
from this description of how we breathe. 

The Air Sacs of the Lungs. —Thus by breathing movements 
the air is drawn into the lungs through the air passages. The 
oxygen finally diffuses down into the finest air tubes. (Fig. 
139.) At the ends of these there are air spaces or air sacs sur¬ 
rounded with extremely thin membrane (see lower part of 
Fig. 133 and also C and D, Fig. 139). Around the air sacs, 
very close to this thin membrane, are many bood capillaries. 
Just as the food passes through the villi of the small intes¬ 
tine into the blood by osmosis,, so in the lungs oxygen passes 
from the air sacs of the lungs into the surrounding blood ca¬ 
pillaries and C0 2 passes from the blood vessels into the air 
sacs, as indicated in Fig. 143. At the cells the exchange of 


196 


The Human Body and Its Enemies. 


oxygen for C0 2 again takes place, as discussed on page 186, 
and again shown in the diagram, Fig. 145. The intimate re¬ 
lation of blood vessels and air sacs is shown in Fig. 144. 

In pneumonia, the disease germs cause an inflammation of 
the lining of the air sacs. In asthma the smaller bronchial 
tubes become partially stopped up, rendering it difficult for 


FIG. 143. FIG. 144. FIG. 145. 



Fig-. 143.—Diagram illustrating respiration in the air sac of the lung. CO 2 
—carboy dioxide; O—oxygen. 

Fig. 145.—Diagram illustrating respiration of a cell at a distance from 
the lungs. 

Fig. 144.—An air sac surrounded by blood capillaries. 

the^patient to get oxygen to the air sacs. How do the germs 
of pneumonia reach the lungs? 

The linings of the air sacs are also injured by alcohol. This 
gets into the blood in the stomach and the intestine and comes 
out into the breath through the air sacs, as proved by the smell 
of the drinker’s breath. The air sacs become inflamed, and, 
therefore, more liable to become diseased and injured for the 
work they have to do. 

The use of cigarettes is so injurious that many States have 
laws against their sale. Their worst damage is to the lungs, 








The Breathing Organs. 


197 


for much of the poison in cigarettes is inhaled and reaches 
the air sacs. 


Summary. 

The organs of respiration consist of the air passages and the 
lungs. Through the air passages the air enters the lungs, being 
warmed and freed from dust on the way. The lungs contain 
the air sacs, hollows at the ends of the fine air tubes. The air 
sacs have very thin walls and are surrounded by meshes of 
blood capillaries. It is here that the blood gives off the C0 2 
and takes on the oxygen. The air in the lungs is renewed by 
the breathing movements of expiration and inspiration, due to 
the action of the diaphragm and the muscles that raise and 
lower the ribs. The air sacs may be injured by alcohol and 
tobacco, the use of which should be avoided. How to prevent 
disease germs from harming the respiratory organs is fully 
treated in the first part of this book. 


Questions. 

1. Where does the air enter the body? 2. Where does oxygen get 
into the blood and CO o leave it? 3. Name the air passages leading 
to the air sacs of the lungs. 4. Give reasons why we should 
breathe through the nose. 5. With a ruler held to your own face, 
indicate how the skull would have to be cut so that one might see 
the irregular bones of the nose shown in Fig. 134. 6. Where do 
adenoids sometimes develop? 7. If affected by adenoids why should 
we have these removed? 8. Why is cartilage tissue needed in the 
windpipe and air tubes? 9. How is voice produced? 10. How does 
the cavity of the mouth and throat help the voice? 11. Point out 
the cilia in Fig. 139. 12. From what part of A, Fig. 139, is the 

section B taken? 13. What is the function of the cilia? 14. How 


198 


The Human Body and Its Enemies. 


is friction of the lungs against the wall of the chest prevented? 
15. C, Fig. 139, is an enlarged portion of what part of A? 16. Sim¬ 
ilarly, explain the relation of D and A. Draw D, Fig. 139, placing 
the blood capillaries about it properly. (See Fig. 143.) 18. State 

two ways by which we breathe; explain fully. 19. Explain the 
meaning of Figs. 143 and 145. 20. How are the lungs often in¬ 
jured? 21. Name several diseases of the lungs and air passages 
and state in each case how the disease may be avoided. 


CHAPTER XXX. 


Ventilation. 

Abundant reasons were given in the previous chapters why 
we need oxygen. Outside air consists of one part of oxygen to 
four parts of nitrogen, as explained in a preceding chapter. In 
more nearly exact figures outside air consists of 20.9 per cent 



Fijr. i46.—A fireplace is effective in ventilating: a room. (Arrows indicate 
air currents.) 

oxygen and 79.1 per cent nitrogen, with only a very slight 
trace of C0 2 . But the air expired from our lungs has only 
16.0 per cent of oxygen, 4.4 per cent of C0 2 and some water 
vapor; the nitrogen remains the same. There is given off of 
the lungs, in addition to these gases, organic matter, and it is 





























































200 


The Human Body and Its Enemies. 


this that makes a room with foul air smell bad. The nose, 
therefore, is a good guide to detect bad air in rooms, provided 
one has first been in the open air; for after any one has been in 
foul air a while, he can no longer detect the bad odor with his 
nose. In that case, however, he can often tell that the air is 
bad from his sick and drowsy feeling and headache. Carbon 
dioxide and organic substances from the lungs and disease 
germs, therefore, poison the air where people breathe and cause 
sickness and, in extreme cases, death. The foul air about us 
should be removed constantly. In the open air the wind car¬ 
ries our foul breath away, but from the buildings we live and 
work in we must remove the foul air and bring in fresh air 
artificially. This process is called ventilation, in what sense 
is breathing a “ventilation of the lungs?” Just as we venti¬ 
late the lungs, so, if we build houses about us, we must venti 
late these houses. 

Every person needs 3,000 cubic feet of fresh air per hour. 
On a cold day this cannot be changed over five times in an hour. 
Every person should, therefore, be surrounded by 600 cubic 
feet of space in the room in which he stays. Figure out how 
far your school room falls short of this standard. 

Principles of Ventilation. —To supply this fresh air, build¬ 
ings like theaters, large churches, office buildings and some 
large schools have electric blow-fans that cause drafts of air, 
previously heated, to blow through the rooms and hallways. 
But we cannot here speak of this means of ventilation. Prac¬ 
tically in our homes, and in most churches and schools, we 
must heat and ventilate without any special fans or air shafts. 
In short, ventilation depends upon the fact that heated air 
rises, because it expands, becomes lighter and is pushed up by 
cold air coming in from all sides, as can easily be seen from 
the following experiments: 


Ventilation. 


201 


Experiments.— (1) Take a common shoe box 
set it on end and cut two holes in it, as shown in 
Fig'. 147. Place a lighted candle on the inside. 
After ventilation has begun, hold a smoldering 
match or a small rag at each hole and note the 
direction of the current as indicated by the 
smoke. (2) Now try the same experiment on the 
school room, if this is heated and the wind is 
not blowing too hard on the outside. Hold a 
burning match or a candle at the top of an open 
doorway or window and at the bottom and note 
the direction of the current in each case. (Fig. 
148.) 

Study Fig. 146 
and state the ad¬ 
vantage of a fire¬ 
place from the 
standpoint of ven- 




Fig. 147. — Experi¬ 
ment with shoe 
box and candle. 


Fig - . 148. — Experiment to 
show outgoing current of 
warm air and incoming 
current of cold air at a 
window. 


tilation. How does the fresh air en¬ 
ter? Where does the foul air go out? 

Prevention of Draft. —From your 
observations on the experiments with 
the shoe box and the candle, how 
would you ventilate by means of 
windows only? You would lower the 
top sash and raise the bottom sash. 
If the stove stands in one end of the 
room, you should ventilate by the 
windows nearest the stove. Why? 

But ventilating by this method is 
imperfect because the warm air 
passes out of the top of the window 
without doing the occupants of the 
room any good; and the cold air 
comes in at the bottom, causing a 




























202 


The Human Body and Its Enemies. 


draft. A better way is to leave the top sash in place, but 
raise the lower one and place a board in front of the open 
space, as shown in Fig. 149. 

Ventilation of School Rooms. —All of these methods may do 
fairly well for homes during the day, for there are not many 
persons in a room at a time, and the doors are opened and 
closed frequently. But for the school room with thirty to sixty 
pupils breathing for some hours at a time, the methods given 
are absolutely inadequate. It is not too much to say that more 
children die from the indirect effects of foul air in the school 
room than from exposure on the way to and from school. 

There is absolutely no excuse except 
ignorance for building a school house 
that cannot be ventilated properly. 
The following points should be kept 
in mind: 

1. Heated air rises. The arrows 
in Fig. 150 indicate the direction of 
the air currents. Describe the ven¬ 
tilation of this schoolroom in class 
with books open. 

2. Fresh air should be furnished, 
but this should first be warmed. 
Where should the inlet therefore be ? 

See Fig. 150. Note that warm fresh air circulates about the 
room. 

3. This warm, fresh air should not be allowed to mix with 
the foul air of the room. The stove should, therefore be sur¬ 
rounded by an iron jacket reaching to the floor. (Fig. 150.) 

4. There should be an outlet for the foul air. This is in 
connection with the chimney, which should have two com¬ 
partments, as shown: one for the smoke, the other for the 



Fig\ 149.—A simple means of 
ventilating- in very cold 
weather. 























Ventilation. 


203 


foul air. The outlet should be near the floor, as shown (Fig. 
150). Why? Draw a picture with an outlet at the top of 
the room and show by arrows how the air would pass out. A 
small fireplace instead of a mere opening is desirable. Other 
details can be gathered from the picture.* 

Outdoor Sleeping. —Many people in Texas, as well as in 



Fig:. 150.—A schoolroom equipped with jacketed stove and ventilating- flue. 
Arrows indicate direction of air currents. Fresh air comes throug-h a 
grate in the floor, passes up between the hot stove and the jacket and 
supplies the room with warm, fresh air. The foul cool air passes through 
a grate in the wall behind the stove, into the foul-air vent of the chim¬ 
ney and thence to the outside. 


all other parts of the civilized world, are sleeping out-of-doors. 
Indeed, patients suffering from such terrible diseases as 
tuberculosis and pneumonia are treated by the fresh air meth¬ 
od. If oxygen is good for one who is sick it ought to be good 


♦Any school board in Texas desiring literature and expert advice 
on the subject of building school houses may obtain both free by 
addressing the State University or the State Superintendent of Pub¬ 
lic Instruction, Austin, Texas. 




























































































































204 


The Human Body and Its Enemies. 


for one who is healthy. How much time do we spend sleep¬ 
ing each day? How many years in a lifetime of seventy is 

this? If all this time were spent 
in fresh air, you can readily see how 
much healthier we should be. Fig. 
151 represents a sleeping porch con¬ 
structed for outdoor sleeping. If one 
cannot have this, it is important 
that one sleep with windows open, 
of course keeping well covered and 
avoiding direct drafts. 

Summary. 

The rooms we live in should be 
well ventilated to keep the air relatively pure. This is almost 
as important as breathing itself. Where many persons stay 
in a room for a long time, as pupils in a school room, there 
should be means of ventilating the room without cold drafts. 
This is best accomplished by means of a ventilating chimney 
and a jacketed stove so arranged as to furnish warm fresh air 
and remove cold foul air continuously. 

Questions. 

1. Why is oxygen needed by the body? 2. How does expired air 
differ from inspired air? 3. What are the harmful substances given 
off by the breath? 4. Define ventilation. 5. How can you tell if 
your school room is poorly ventilated? 6. Explain Figs. 147 and 
14 8. 7. Mention some rules for ventilating an ordinary room. 8. 

Fully explain the circulation of air in Fig. 150. 9. Where does 

the fresh air come in? 10. Where does the foul air pass out? 11. 
How is the foul air of the room kept from mixing with the fresh 
air coming in under the stove? 12. What are the special advan¬ 
tages of sleeping out-of-doors? 



Fig. 151.—A sleeping porch 
Suitable for Texas. 





CHAPTER XXXI. 


The Circulation of the Blood. 

In the preceding chapters much was said about the blood 
and the lymph and their functions. At this stage of your 
study, it is perfectly plain to you that the main function of 
the blood is to carry the useful ma¬ 
terials of food and oxygen to the 
cells of the body and to take away 
the harmful waste substances. Fig. 

152 represents the relation of a body 
cell to the blood and to the lymph. 

The bood flows in a system of 
closed tubes. It is the thinnest and 
smallest of these, the capillaries, that 
carry the blood close enough to the 
cells of the body so that the food and 
waste substanecs may be exchanged 
between the blood and the cell. The 
lymph surrounding cells and capilla¬ 
ries forms the medium through 
which the food and waste materials pass to and from the 
cells. Capillaries also come close to the cells of the glands 
(Fig. 117), the villi (Fig. 122), and the air sacs of the lungs 
(Fig. 144), as has been shown. In short, the capillaries of 
the blood come close to each and every living and working 
cell of the body. 



206 


The Human Body and Its Enemies. 


(A PULA *IC3 or Ll/flOS 


The Blood as a Carrier. —To take on a load of food or oxygen 
the blood must go to the proper organ to get it, just as your 
grocer must go to the freight depot to get the groceries before 
he can supply you with them. To the supplying organs the 
blood is pumped by the heart: first to the lungs, where it re¬ 
ceives its load of oxygen. Here the arteries break up into 
capillaries which surround the air sacs. 
Through the thin capillary wall and the thin 
walls of the air sacs the blood takes on oxy¬ 
gen and gives off carbon dioxide. The oxy¬ 
genated blood then goes back to the heart 
to be pumped out again to all parts of the 
body. Similarly, the blood passes through 
the stomach and the small intestine and 
takes on food, which is carried to the heart 
to be pumped out to all of the cells. 

The Lesser and the Greater Circulation.— 
It is to be noted that a special trip is made 
to the lungs; the blood goes to these organs 
and then straight back to the heart. This is 
the lesser circulation (Fig. 153). When the 
blood starts out again from the heart it goes 
to all parts of the body, passes through the 
capillaries among the cells and returns again 
to the heart. This is the greater circulation. 
(Fig. 153.) 

In short, the heart pumps blood into arteries, these break 
up into capillaries in the lungs and other parts of the body, 
and the capillaries combine to form veins, which return the 
blood to the heart. It is easy to see how the blood is forced 
out by the pumping action of the heart, but it is not so easy 



CAPILLARieS or «opv 


Fig-. 153.—The less¬ 
er circu 1 a t i o i, 
(thr ough the 
lungs) and the 
greater circula¬ 
tion (through the 
body). 




The Circulation of the Blood. 


207 


to see how the blood is forced back to the heart. In this 
chapter we shall study more about the circulation of the blood. 


Observation on the Circulation of the Blood.—If you hold your 
hand up to a bright light you see the red color plainly through the 
skin. But you cannot see the blood flow. If you chop a chicken’s 
head off, the blood will run out and the blood will “flow;” but 
this is not circulation. Very favorable subjects for studying the 
circulation are the thin web of a frog’s foot, and the thin mem¬ 
brane at the sides of a 
tadpole’s tail. To see this 
requires a compound mi¬ 
croscope. But the sight 
is so beautiful that it is 
well worth while going to 
some trouble to have a 
high school teacher or a 
local physician bring his 
microscope and show you 
the sight. Tadpoles can 
be found in permanent 
pools of water at almost 
any season in Texas. Se¬ 
cure one and put it in 
place, as in Fig. 154. The 
tadpole is lightly covered 
with cotton (C) kept wet 
with water. The piece of 
tin is bent at right angles and has a hole (H) through which 
the tail of the tadpole protrudes. This hole should not be so large 
as to allow the animal to slip through. The tail is laid over the 
slit (S) in the shingle so as to let the light through in viewing a 
thin part of the tail, as at point X, with a microscope. Here the 
circulation of the blood can be well seen. A thread may be strung 
over the tail to keep it from flipping up during observation. If 
you are fortunate enough to see this, note that the blood flows 
through the capillaries in a steady stream and not in jerks. 



Fig:. 154.—Showing: manner of mounting: a 
tadpole to observe the circulation of blood 
in arteries, veins and capillaries. (See 
text.) 


How the Blood Circulates. —The word circulate means to 









208 


The Human Body and Its Enemies. 


travel in a circle. When we say the blood circulates we imply 
that it continues to return to its starting point. We noted 
above that this is the case. The blood is forced on its journey 
by the heart. Prom the heart the blood travels in arteries. 
These arteries divide into smaller and smaller branches until 

the finest hair-like arteries be¬ 
come capillaries. (Fig. 155.) The 
capillaries combine to form veins, 
which continue to unite as they 
proceed to the heart. The blood 
passes through two sets of capil¬ 
laries on one complete round 
through the body: through the ca¬ 
pillaries of the lungs, and through 
the capilaries in different parts of 
the body, but each time return¬ 
ing to the heart to be pumped out 
again, as shown in Fig. 153. In what sense are there two cir¬ 
culations? In what sense is there really but one complete cir¬ 
culation ? 

The Heart. —The heart has a single duty to perform: to pump 
blood. It is, therefore, composed largely of muscle and con¬ 
nective tissue. It is located in the thorax, between the lungs, 
just a little to the left of the middle line, with the point di¬ 
rected to the left. (Fig. 80a and Fig. 156.) We can “feel” the 
beat of the heart between the fifth and sixth ribs. As this 
organ is in motion a large part of the time we would expect 
it to be protected against friction? How are the lungs 
protected against friction? The stomach and the in¬ 
testine? Name the coverings of the lungs and of the abdom¬ 
inal organs. The heart is likewise covered by a two-layered bag, 
the pericardium, with a lubricating liquid between the layers. 



Fig - . 155.—A net work of blood 
capillaries connecting- an ar¬ 
tery with a vein. 



The Circulation of the Blood. 


209 


The heart is divided into fwo halves by a solid partition 
wall. No blood can pass from one side of the heart to the 
other except by going around through the capillaries. What 
capillaries must the blood pass through to go from the right 



Fig - . 156.—A view of the principal arteries and veins. 1, right ventricle; 
2, right auricle; 3, part of left ventricle; 4, corner of left auricle; 5, pul¬ 
monary artery (to lungs); 6, aorta; 7, vena cava descending; 8, vena cava 
ascending; 9, renal artery (to kidney); 10, renal vein (from kidney); 11, 
right and left subclavian veins; 13 and 16, left and right arteries; 12, 
jugular veins; 14 and 15, left and right carotid arteries; 18, veins from 
abdominal organs; 19, arteries to abdominal organs. 

Fig. 157.—Left side heart, with left ventricle (3) and auricle (4) cut open. 
20, two of the four pulmonary veins, from lungs; 21, valves of pulmo¬ 
nary artery (5), almost closed; 24, similar valves of the aorta (6), with 
part of the aorta cut away; 22, valve between auricle and ventricle; 23, 
cords and muscles holding the valves. 


to the left side? (Fig. 153.) Each half of the heart consists 
of a thin-tvalled chamber called the auricle, to receive the 
blood, and a thick-walled chamber called the ventricle, to 
pump the blood out into the arteries. How many chambers has 











210 


The Human Body and Its Enemies. 


the heart? Name them. Two large veins bring the blood 
back to the heart from all parts of the body: the descending 
vena cava, from the upper part of the body (7 Fig. 156), 
and the ascending vena cava, from the lower part (8). One 
pulmonary artery (5) leaves the right ventricle for the lungs, 
and four pulmonary veins (20) carry the blood back to the 
left auricle. One large artery, the aorta (6), takes the blood 
out of the left ventricle to all parts of the body. How many 



Fig. 158.—Diagrams of heart, showing action of valves: A, at expansion 
of heart; B, at beginning of contraction. Diagrams a and b illustrate 
action of valves between auricle and ventricle. 


veins come into the heart? How many arteries leave the 
heart ? 

The Action of the Heart.— After the blood has come into 
both of the auricles, these contract and push the blood into the 
ventricles. Then the ventricles contract, pushing the blood 
into the arteries. The contraction of the ventricles constitutes 
the “heart beat.” Since the arteries are already full, pump¬ 
ing more blood into them makes them expand; this expansion 













The Circulation of the Blood. 


211 


is called the pulse. Since this happens at every heart beat, you 
can count the heart beat by feeling the pulse. That the blood 
does not go back into the auricle during the contraction of the 
ventricles is due to the presence of flaps of connective tissue, 
so placed and held by cords (Fig. 158 A) that the blood catches 
under the flaps and closes them after the manner of Fig. 158 B. 
This is illustrated further by diagrams a and b of the same 



Fig-. 159.—Valves in aorta. (Compare with Fig. 157.) 

Fig:. 160.—Valves shown in Fig. 159, closed, as seen from within the aorta. 
Fig-. 161.—A vein with several branches laid open, showing- valves. 


figure. So, too, when the ventricles expand and rest between 
beats, the blood, under pressure in the arteries, tends to gush 
into the ventricles. It is prevented from returning, however, 
by pockets fastened to the walls of the arteries shown at 24 in 
Fig. 157, and again, more enlarged, in Figs. 159 and 160. Such 
flaps or pockets that make the blood go in one direction are 
called valves. Point out the valves of the heart in the illustra¬ 
tions, and explain how each acts. How many sets are there? 

Observation Work.—1. Find the pulse on your wrist and count the 
number of heart beats per minute. (2) Listen to the heart beat of 




212 


The Human Body and Its Enemies. 


some person by pressing your ear against the chest or back on the 
level of the heart. You will hear two sounds at each beat. These 
are partially due to the closing of the valves, the “slamming of the 

doors.” Which valves close to make 
the first sound? (Remember that 
the right and left ventricles contract 
and expand together.) 

(3) Study Figs. 162 and 156 and 
trace the blood in a circuit through 
the body. Trace it from the head 
back to the head; from the lungs back 
to the lungs; from the liver back to 
the liver. 

There is one vein that deserves 
special mention. It is the portal 
vein. (Fig. 123.) It begins in ca¬ 
pillaries in the stomach and intes¬ 
tine and ends in capillaries of the 
liver. It is the only blood vessel 
in the body beginning and ending 
in capillaries. Where do all other 
veins begin and where end? Ar¬ 
teries? What substances pass 
through the portal vein? 

Arteries and veins differ, as has 
been seen, in the direction of their 
flow. Which flows away from 
the heart? They differ also in the thickness of their walls. 
(Fig. 163.) The veins have less elastic connective tissue and 
muscle than the arteries. The veins, furthermore, have valves 
throughout their course, as shown in Fig. 161. Where are the 
only valves in the arteries? (Fig. 157.) 

In the arteries the blood is under pressure. When an ar¬ 
tery is cut, therefore, the wound stands open, blood spurts 


CAPILLARIES of 
VPPLR PART OF BODY 



Fig. 162.—Diagram of the 
circulation of the blood 
(compare “with; Fig. 
153). 




The Circulation of the Blood. 


213 


out and a person is in great danger of bleeding to death. The 
arteries are placed deeper under the skin and muscles than the 
veins. When an artery is cut, to stop the bleeding, press¬ 
ure should be applied between the cut 
and the heart, as has been described in 
Chapter XLV. 

How the Blood Gets Back to the Heart. 

—Contraction of the heart and elasticity 
of the arteries send the blood coursing 
toward the capillaries, where the blood 
does the main work. Now let us see how 
the blood is forced back to the heart. The 
pressure from the arteries pushes the 
blood through the capillaries into the 
veins. But this is not sufficient to carry 
the blood very far on its way to the heart, 
especially from the feet, for example. The 
blood is helped along in two ways: It 
is partty sucked and partly squeezed on 
its way. At every inspiration, the chest 
is expanded, which causes the blood to 
be drawn to- 
w a r d the — 
chest. The ^ 

ve i n s are 

Squeezed 164, —Valves in vein, Fig-. 165.—Valves in vein, 

. open. closed. 

every time a 

muscle contracts and becomes hard and firm. Now the blood 
tends to flow backwards from the heart as well as forwards to¬ 
ward the heart, and is prevented from flowing backwards by 
the valves in the veins as illustrated by the accompanying 
diagrams (Figs. 164 and 165). 




Fig-. 163.—Cross sec¬ 
tion of artery, vein 
and two capillaries. 
E, epithelial lining- 
(the only tissue in 
the capillaries); ET, 
elastic ' tissue; M, 
muscle tissue. 






214 


The Human Body and Its Enemies. 


Observation Work.—You can easily locate the valves in a vein on 
the back of your hand or on your wrist. Hold your hand down 
and press the muscles of your forearm on the edge of the desk. 
This will make the veins of the back of your hand stand out. Now, 
with the blunt end of your pencil, press along a vein toward the 
fingers (away from the heart) and note that the vein does not fill 
from the end toward the heart. 

You yourself can now tell why deep breathing is beneficial to 
the organs of circulation. State also how exercise helps the 
flow of blood through the muscles, and why the muscles used a 
great deal are darker* than others. For the same reason rub¬ 
bing a part of the body helps to increase the circulation. 

Summary. 

The blood circulates in a system of closed tubes: the heart, 
to pump the blood; the arteries to carry the blood to the ca¬ 
pillaries ; these to connect the arteries with the veins; and the 
veins to carry the blood back to the heart. The capillaries are 
short and thin-walled; it is in the capillaries, therefore, that 
the blood exchanges food for waste substances with the cells. 
The blood is partly forced back to the heart by the pressure 
of the muscles against them, and by the action of the valves 
that prevent the blood from flowing backwards. Exercise, 
therefore, helps the flow of the blood. Exercise also helps the 
blood to return to the heart in that it requires deep breathing, 
for the breathing movements suck the blood toward the chest, 
and therefore toward the heart. 


♦Compare, for example, the breast and the leg muscles of a 
chicken. 



The Circulation of the Blood. 


215 


Questions. 

1. What is the chief function of the blood? 2. In what blood 
vessels does the blood take on and give off its loads? 3. What does 
the blood take on (a) in the lungs? (b) in the stomach? (c) in 
the intestine? (d) from the various cells of the body? 4. What 
does the blood give off at those cells? 5. What does it give off in 
the lungs? 6. What is meant by the lesser circulation? 7. Name as 
many differences as you can between arteries and veins. 8. Of 
what tissue is the heart chiefly composed? 9. When does the heart 
“rest?” 10. What is meant by pulse? 11. From Fig. 15 8 describe 
the action of the heart in pumping blood. 12. What is the use of 
the valves between the auricles and the ventricles? 13. What is 
the use of those at the openings of the arteries? 14. How many 
times does your heart beat each minute? 15. Where is the portal 
vein and what does it carry? 16. Tell how the blood gets back to 
the heart. 17. How does exercise help the circulation? 18. How 
does deep breathing help the blood flow? 19. Trace the blood from 
the right auricle to the left ventricle. 20. Trace it around to other 
parts of the body as the teacher may direct. 


CHAPTER XXXII. 


The Blood and the Lymph. 

What the Blood Is. —We have seen that the blood is the car¬ 
rying agent of the body, carrying food and oxygen to the cells 
and waste matter away. Most of these substances are carried 
simply in solution, for blood is largely water containing dis¬ 
solved substances. 

Review Work.—Make a list of all the substances you would ex¬ 
pect to find dissolved in the blood, studying in this connection pages 
179 to 183, and Figs. 125 and 128. 

Blood contains certain cells called corpuscles: red and white. 

They are extremely small, 
one small drop the size of a 
pin head containing several 
million red ones and thous¬ 
ands of white ones. The red 
corpuscles are of the shape 
shown in Fig. 166. B, C, and 
D of this figure show red 
corpuscles, highly magnified, 
in flat view, end view and 
oblique view. Describe the 
shape from these drawings. 
White corpuscles are shown 
at F and G. The blood is easily studied with a large microscope 
and should be seen if possible. The subject will certainly be 
a revelation to you, for who would think, after looking at a 



Fig'. 166.—Blood corpuscles, hig-hly 
magnified. B, C, D, red, and F, G, 
white blood corpuscles. 


The Blood and the Lymph. 


217 


drop of blood with the naked eye, that it is made up of so 
many and so wonderful things ? 

The red corpuscles are just of the right size to pass through 
the capillaries single hie, as can plainly be seen in the tad¬ 
pole’s tail (page 207). Now, when you are told that it is the 
duty of these little cells to carry oxygen from the air sacs of 
the lungs you will readily see why they must pass single file. 
At a circus the crowd passes in single file by the ticket window 
to get the tickets, and in the same way deposits the tickets at 
the entrance. Copy Figs. 143 and 145 and add to your draw¬ 
ing red corpuscles in the capillaries. 

Just how the corpuscles carry oxygen 
is not easy to understand. Oxygen in the 
air is a gas, and in that condition a little 
oxygen takes up a great deal of room. The 
oxygen “makes itself small” by uniting 
with a substance called hemaglobin, which 
is found in the red blood corpuscles. When 
there is much oxygen present, as in the 
air sacs of the lungs (Fig. 143), the hem¬ 
aglobin causes the oxygen to unite with 
it, and in this condition the oxygen takes 
up almost no room. But the oxygen will 
easly let go of the hemaglobin when the 
blood reaches a place where oxygen is 
scarce, as out among the working cells of 
the body. (Fig. 145.) 

The white corpuscles differ from the 
red ones in that they can change then- 
shape, and also in that they have quite a 
different work to do. They are the “soldiers” and “scaven¬ 
gers” of the body. What is a soldier’s duty? A scavenger’s? 



Fig-. 167.—Blood vessel 
of frog, showing how 
white blood cor¬ 
puscles pass out of 
the blood vessel. A, 
corpuscle within the 
vessel; B, partly and 
C, entirely outside 
the vessel. R, red 
corpuscle. 


218 


The Human Body and Its Enemies. 


The white corpsulces fight for us, swallowing and digesting 
the disease germs in the body. (Fig. 15.) They likewise take 
up fragments of worn-out protoplasm lying among the cells. 
If you stick a splinter in your finger, the white corpuscles 
travel to. the spot and try to surround the splinter and get rid 
of it by “festering” it out of the body. For these corpuscles 
can get out of the capillaries by squeezing through them be¬ 
tween the cells just as you would squeeze a large-sized rubber 
ball through a small crack in the fence. (Fig. 167.) 

Where the Corpuscles Are Pro¬ 
duced— Both kinds of corpus¬ 
cles are continually being worn 
out and new ones produced. 
The red ones are made by cer¬ 
tain cells in the red marrow of 
flat bones and in the spleen; 
white ones by certain cells in 
the spleen and lymph glands. 
What happens to the body if 
we have too few white blood 
corpuscles? What do the cells 
lack if the blood has too few 
red ones? If the red ones are 
scarce in the blood of a person he is said to suffer with anemia. 
In malarial fever the germs destroy the red corpuscles; hook¬ 
worms use up a great deal of a person’s blood. A patient suf¬ 
fering with either disease is anemic and shows it by a pale or 
sallow complexion. It is, therefore, important that we should do 
everything to help the body produce many corpuscles. Plenty 
of fresh air, good food, sleep and exercise are conducive to the 
production of blood corpuscles. 

Clotting of Blood. —How does the blood act when it runs out 





The Blood and the Lymph. 


219 


of a cut or other wound? It clots, you say. This is due to the 
strands of fibrin (Fig. 168), a kind of proteid, separating out 
or coagulating, just as the white of an egg, another kind of 
proteid, coagulates on heating. There is a proteid in the blood 
that coagulates and changes to fibrin merely on exposure. 

Observation Work.—Leave a bottle at the 
butcher’s, with the request that he have it filled 
with ox blood. When you call for the bottle 
and take it to school, a dark red clot will have 
formed. (Fig. 169.) What does this clot con¬ 
sist of? (Compare Fig. 166 with Fig. 168.) 

The straw-colored liquid on top is serum; this 
contains water, foodstuffs and wastes in solu¬ 
tion. It also contains antitoxins when these 
are present in the blood. (Fig. 128.) 



The Lymph. — There is another fluid in the Fi& . m —a tumble 
body very much like the blood, namely, the of clotted blood ' 
lymph. Read again pages 179 and 180 and 
describe where the lymph is found. Lymph differs from blood in 
that it lacks red corpuscles and clots more slowly. Perhaps you 
remember when last you had a blister from a burn. The blister 
was filled with thin lymph. The fluids in the pericardium, be¬ 
tween the pleurae and around the abdominal organs are kinds 
of lymph. 

After studying Fig. 152 you must come to the conclusion 
that the function of the lymph is to fill the spaces among the 
cells of the body and to form the means of communication be¬ 
tween the cells and capillaries. Which substances are given 
to and which taken from the cells in Fig. 152 ? A little thought 


will also tell you where all of the lymph probably comes from: 
it oozes out of the blood capillaries, and is, we might say, the 
liquid part of the blood. The cells also add waste sub¬ 
stances to the lymph. The lymph helps the blood to carry off 


these wastes. 





220 


The Human Body and Its Enemies. 


Lymphatics. —Now the lymph must be constantly renewed 
and therefore constantly drawn off. It does not pass back into 
the blood through the capillaries, but has vessels of its own, 
the lymph capillaries and lymph veins, that carry the lymph 
away. The lymph capillaries run out from the lymph spaces 
(Fig. 170) and then unite into veins just as the blood vessels do. 

The lymph veins all finally 
unite into two large lymph¬ 
atic ducts, the larger of 
which is on the left side, and 
is called the thoracic duct. 
Fig. 171 tells where the two 
ducts are located. Note that 
they empty into large veins 
above the heart, where the 
lymph again mixes with the 
blood. Lymph, therefore, 
comes mainly from the blood and runs back into the blood. 

There is another special starting point for the lymph . Re¬ 
view what was said about the lacteals and tell where they are 
and what these lymph vessels carry into the blood. The lac- 
teals unite and empty into the thoracic duct. (Fig. 123.) 

Lymph Nodes. —On their way the lymph veins pass through 
knots of tissue special organs called lymph glands, or lymph 
nodes. Here certain changes occur in the lymph ; disease germs 
are stopped here and kept from going into the blood. The 
lymph nodes also produce corpuscles, as mentioned above. The 
spleen is a large lymph node. Fig. 171 shows the location of 
some of the lymph nodes of the body. Fig. 172 represents a 
single one cut open. Note that the lymph vessels have cross 
lines on them. These show the location of valves, the use of 
which is exactly that of the valves in the veins. The sucking 



Figr. 170.—Lymphatic capillaries 
(L) beginning in the lymph 
spaces among cells of the body. 



Tiie Blood and the Lymph. 


221 


action of breathing and the contraction of the muscles force 
the lymph along exactly as the blood is forced along in the 
veins. 

Observation Work.—Have one pu¬ 
pil stand absolutely still until he 
gets tired and at the same time have 
another pupil walk slowly about. 

Why is it harder to stand perfectly 
still than to walk? 

Hygiene of Circulation 

Exercise. —We have noticed that 
the contraction of the muscles 
helps the circulation in that it in¬ 
creases the flow of the blood in 
the veins and of lymph in the 
lymphatic vessels. Exercise fur¬ 
ther helps the circulation by in¬ 
creasing the number and depth of 
the breaths. But it also helps in 
exercising the heart. 

Experiment to show the effect of 
exercise on the heart. Count the 
pulse after fifteen minutes of rest. 

Stand up one minute and make a count; walk a minute and count 
again; run or hop a minute and make another count. Why does 
exercise make the heart beat faster? Review pages 181 and 185 
before trying to answer this fully. 

We must exercise the heart, otherwise it will give out in 
cases of emergency, such as sickness or having to run to catch 
a train. So we should exercise every day sufficiently to make 
the heart beat strongly for a while. But we must guard 
against too severe exercise, such as boys and girls in the gram¬ 
mar grades are likely to engage in. At this age the heart grows 



Fig. 171.—The lymphatic sys 
tem. LAC, lacteals. 






222 


The Human Body and Its Enemies. 


very fast. Foot racing, bicycle riding, football and even tennis 
may easily be overdone. Grammar school boys should not 
attempt to run more than a fifty-yard dash or a one-fourth 
mile relay race. 

Alcohol. —Alcohol makes the heart beat faster and so inter¬ 
feres with nature’s way of regulating the beat, and thus over¬ 
works the heart. It makes the blood vessels of the skin en¬ 
large and so forces more blood into the skin, which thus be¬ 
comes red. Since there is more blood in the skin the body 


cools off faster and is there¬ 
fore not warmed but cooled 
by alcohol. In cold weather 
what kind of food should be 
taken in place of alcohol? No 
one who uses alcohol could 
ever reach the North or the 
South Pole. It is said that 
alcohol taken in small quan¬ 
tities makes a person “fat.” 



But this fat is unhealthy, 
^vessels” A lymph node ’ with lymph and if the fat is deposited 

about the heart, it becomes 
dangerous. Many deaths occur from diseases, notably pneu¬ 
monia, because the heart fails to do its duty. You have heard 
it said of a sick person, “Tomorrow will come a turning point 
in the disease,” or “If he lives until tomorrow, he will get 
well.” How necessary it sometimes is to have a heart that 
will hold out just one day longer! We cannot afford to do any¬ 
thing that will injure this wonderful organ, the heart. 

Tobacco. —Doctors speak of an “alcohol heart” and a “to¬ 
bacco heart:” an unsteady, palpitating, fluttering, unreliable 
heart. Tobacco is particularly harmful to the young boy of 


The Blood and the Lymph. 


223 


grammar or high school age. At that time the heart grows 
rapidly, and any interference is sure to lead to permanent in¬ 
jury. If a boy thinks he must smoke, he should wait until he 
is at least twenty-one. 


Summary. 

The blood contains red corpuscles and white ones. The red 
corpuscles have to do with respiration, for they carry oxygen 
from the lungs to the cells of the body. The white corpuscles 
have to do with fighting of disease germs in the body. The 
number of both kinds of corpuscles is increased by correct 
habits of living. The blood also contains a proteid that forms 
fibers of fibrin, which makes blood clot. The lymph surrounds 
the cells of the body. It is moved along and collected in lymph 
vessels that empty into the blood vessels above the heart. Ex¬ 
ercise is necessary to strengthen the heart and to improve the 
circulation generally by contraction of the muscles and by 
deep breathing. Alcohol and tobacco affect the heart and ar¬ 
teries, often injuring them permanently. 

Questions. 

1. What have the red corpuscles to do with respiration? 2. What 
is the work of the white corpuscles? 3. In what organ of the body 
is each kind of corpuscle made? 4. What is anemia? 5. How do 
hookworm or malaria cause anemia? 6. What is the value of clot¬ 
ting of blood? 7. What is serum? 8. What parts of the blood does 
the clot (Fig. 169) contain? 9. Where is lymph found in the body? 
10. Describe a lymph vessel. 11. Is it more like a vein or an ar¬ 
tery? Why? 12. What does the thoracic duct carry? 13. Where 
does it empty? 14. What are the lymph nodes? 15. How does exer¬ 
cise help the flow of lymph? 16. How does exercise help the heart? 
17. Why is it dangerous for young boys to exercise too violently? 


CHAPTER XXXIII. 


Excretion. 


The Meaning of Excretion. —We have thus far considered a 
number of activities of living cells, for example, the taking of 
food, assimilation, growth, respiration. You should be able 
to tell in your own words what each of these means. Diges¬ 
tion, absorption, assimilation, growth are all building-up pro¬ 
cesses which end in the making of protoplasm by the cells of 
the body. Then oxygen comes to the cell and burns up the pro¬ 
toplasm and the foods, and thus tears down or breaks up the 
protoplasm. Oxidation is a tearing-down process, but it is 
necessary in order that energy for warmth and motion may be 
produced. But not only is energy produced but waste sub¬ 
stances result from oxidation. The production of waste -sub¬ 
stances is called excretion. Every cell excretes waste substances 
(Fig. 152), and the blood carries them to the proper organs 
which remove them. The organs that remove waste substances 
from the blood are called excretory organs. 

The Waste Material of the Cell. —We have already studied 
one set of excretory organs,* the lungs, which remove carbon 
dioxide from the body. Respiration thus includes two phases: 
the taking in of oxygen and the removing of carbon diox- 


*We shall not include here the large intestine that removes undi¬ 
gested foods, worn-out digestive juices and bacteria from the ali¬ 
mentary canal. It is, of course, of extreme importance to health 
that decaying remnants of the food should be removed daily from 
ihe body. 



Excretion. 


225 


ide. (Fig. 129.) The lungs are, therefore, in a sense, organs of 
excretion that remove most of the used-up carbon from the 
body. 

Another important waste substance is that containing nitro¬ 
gen, and is called uric waste. This is removed by the kidneys 
and by the sweat glands of the skin. 

Thus it is seen that there are two main kinds of waste sub¬ 
stances : carbon dioxide, containing most of the carbon removed 
from the blood by the lungs, and uric waste, containing all of 
the nitrogen and removed from the blood by the kidneys and 
skin. 

The liver is sometimes included as an excretory organ; but 
this is only partly correct. It does not remove waste substances 
but changes them to a form more easily removed by the kid¬ 
neys and skin. 

The Kidneys. —The location and shape of the two kidneys 
can be seen in Fig. 80a; also at 16, in Fig. 156. Fig. 173 repre¬ 
sents one kidney, opened, showing the internal structure. As 
the uric waste is carried to the kidney by the blood there are, 
as we would expect, a large artery (renal artery) leading to 
the organ, and a large vein (renal vein) carrying the blood 
away. (9 and 10, Fig. 156.) Which of these, artery or vein, 
has the smaller amount of impurities in it? So you see that 
arteries do not always carry “purer” blood than the cor¬ 
responding vein. Give another example of this occurrence. 

The kidney is made up of a very large number of fine tubes 
or tubules that begin near the outer surface as little pockets of 
epithelial tissue. The pockets are indicated by dots (C, Fig. 
173), and the tubules by lines (PY). These tubules pass to¬ 
ward the hollow of the kidney at H. Four tubules, enlarged, are 
shown at T in the same figure, two near the top and two near the 
middle of the section represented. From Fig. 174 the course of 


226 


The Human Body and Its Enemies. 


the capillaries of the blood can be seen. A bunch of capilla¬ 
ries (Cap. 1) enters the pocket at the head of the tubule, and 
more capillaries surround the tubule itself (Cap 2). The cells 
that take water and waste substances out of the blood are 
the cells shown at X, Y and Z. The kidney is in a sense a 


FIG. 173. 


FIG. 175. 


FIG. 174. 



Fig:. 173.—Vertical section of a kidney; H, hollow of kidney, communi¬ 
cating: with ureter. T, tubules (much enlarged) beginning: in pockets 
and emptying in hollow H. PY, masses of tubules beginning in pockets 
in region C. 

Fig. 174.—Tubule and pocket of kidney, much enlarged. X, epithelial tis¬ 
sue of pocket, Y and Z of tubule. Cap. 1, blood capillary of pocket; Cap. 2, 
capillary of tubule. 

Fig. 175.—A portion of tubule much more enlarged. Y, cells of tubule. 


gland. By comparing Fig. 175 (a part of a tubule much 
magnified), with the gland shown in Fig. 118, you may easily 
see how much the tubule of the kidney is like a gland. 
We have here another example of the close relation of work¬ 
ing cells to the blood capillaries. The waste substances here 
removed by the kidney cells are emptied into the hollow 











Excretion. 


227 


of the kidney at H, Fig. 173, thence through the ureter into 
the bladder. 

Hygiene of the Kidneys. —There are not many points to be 
remembered in the hygiene of the kidneys. It is likely that a 
large percentage of the kidney diseases which occur are due 
indirctly to the germ diseases like scarlet fever and smallpox. 
The kidneys have to filter out the poisons which the germs 
form in our bodies, and this work is damaging to the kidney 
cells (X, Y, Z, Fig. 173). The best way to take care of the kid¬ 
neys is to take care of the body itself. 

It is wise to drink a great deal of water at all times, as this 
dilutes the poisons which are thrown off by the kidneys. It 
seems reasonable to believe that all irritating substances which 
pass out through the kidneys, such as alcohol, the oils from 
hot condiments and spices, like mustard or horse radish, would 
also irritate the kidneys, and, in the long run, damage them. 
Fried food contains certain irritating substances which are the 
result of the burning of the grease, and these substances must 
be thrown off by the kidneys; hence fried foods are burden¬ 
some to the kidneys. Lastly, sudden and extreme changes in 
temperature may injure the kidneys. 

Summary. 

The pair of kidneys are the chief excretory organs of the 
body for the removal of uric waste. They are richly supplied 
with blood vessels. A study of the finer structure of the kid¬ 
neys shows them to be true glands, for the capillaries of 
the blood enter pockets of gland tissue and surround tu¬ 
bules of the same kind of tissue. The gland cells take the 
waste material out of the blood and pass it on to larger 
tubes emptying into the hollow of the kidney. Alcohol and 


228 


The Human Body and Its Enemies. 


toxins of disease germs are especially injurious to the gland 
cells of these organs. 

THE SKIN. 

Description of the Skin. —The skin is a double covering of 
the body. The thinner outer skin, the epidermis (Fig. 176), is 



Fig'. 176.—A block of skin about the size of a small grain of corn magnified. 
Pyr, living- layer of epidermis. Below this layer is dermis. PD, papil¬ 
lae of dermis. TB, touch bud in papilla; N, nerve; CAP, blood capillary. 
B, coil of sweat glands; EG, portion of duct of sweat gland, more en¬ 
larged; CS, cross-section of sweat duct; F, hair follicle; OG, oil glands; 
'M, muscle of hair; C, connective tissue of dermis. 


made up of horny cells, with the exception of the lowest layer. 
This layer (PYR) produces all of the others as fast as these 






















Excretion. 


229 


are ordinarily worn away. The epidermis contains few nerves 
and no blood vessels. The inner or true skin, the dermis, is 
made largely of connective tissue (C) ; this is, therefore, the 
part of the skin of animals that is made into leather. It is 
richly supplied with blood vessels, and there are many fat cells 
scattered through it. The fat helps to keep animals warm; 
the whale, for example, has a thick layer of fat under the 
skin so as to keep warm in the icy waters of the cold seas. 
Some nerves end in certain cells placed where the dermis 
projects up into the epidermis; these projections, or papillae, 
contain the nerves of touch (N), with which we feel things, that 
is, distinguish hard and soft, wet and dry, sharp and dull, 
etc". With other nerves in the skin we distinguish heat and 
cold. The blood vessels are present to perform their usual 
duty of serving the wants of the living cells. They must, in 
the first place, bring material with which the living layer of 
epidermis can grow and multiply and produce more cells to 
take the place of those worn off. The mass of cells worn off 
in the course of a year, if they could be collected, would fill a 
basket of considerable size. Dandruff is simply masses of skin 
cells from the scalp. To furnish materials to renew the worn- 
off cells, the blood comes through the dermis close to the 
living layer of the epidermis. (Cap, Fig. 176; also C, Fig. 228.) 
The blood also carries material for other organs, the hair and 
the sweat glands, that reach down from the epidermis into 
the dermis. 

The Hair. —The hair is horny, like the epidermis; in fact, it is 
produced by epidermal cells that extend down into the dermis 
like a kind of socket. In this socket, called the hair follicle 
(Fig. 176), the hair stands. At the bottom of the follicle is 
a mass of cells that grow and multiply rapidly, adding to the 
hair, pushing it out as it grows. Hair thus grows from the 


230 


The Human Body and Its Enemies. 


bottom, or “root,” which is richly supplied with blood. Hair 
has attached to it two organs; first, a muscle (M), which by 
contracting, can make the hair stand on end. A dog or a cat 
uses these at will, making the hairs on its back “bristle up” 
when angry. The other organ in connection with the hair is 
one or more oil glands (OG), which empty oil into the hair fol¬ 
licle. You have noticed how a leather harness cracks and 
breaks when not kept oiled; the skin and hair, too, must be 
oiled to keep them fresh and pliable. 

The finger nails and the toe 
nails are also horny like the epi¬ 
dermis, but unusually thick. They 
are produced from cells at the 
base or root of the nail, and are 
pushed forward as they grow. 

(Fig. 177.) The nails should be 
trimmed even with the fingers, but 
no further. Dirt that collects un¬ 
der the nail should be removed 
with a dull instrument, not with a sharp knife, for this rough¬ 
ens the under surface of the nail and makes dirt gather still 
more easily. Stains on the surface may often be removed with 
vinegar. 

The Sweat Glands. —Other extremely important organs of 
the skin are the sweat glands. These are simply tubes running 
down from the surface, through the epidermis, and for some 
distance into the dermis. They are coiled up at their lower 
ends. The coil (B, Fig. 176) is surrounded by a network of 
blood capillaries, as is seen in diagram 5, Fig. 117, and again 
in Fig. 178. The epithelial tissue of the sweat gland comes in 
close contact with blood capillaries, as is the case with all 
glands. The sweat gland is coiled up in the dermis (B) because 



Fig. 177.—Longitudinal section 
of end-joint of finger. 




Excretion. 


231 


it is so long; there would not be room in the skin if all the sweat 
glands were stretched out straight. 

The sweat glands remove from the blood sweat or perspira¬ 
tion,, which consists of water with salt and a little waste sub¬ 
stances dissolved in it. They are thus in part excretory, and 
each sweat gland may be compared to a single tubule of the 
kidney. (Compare SEG., Pig. 176, with Fig. 175.) How are 
they alike in structure? But 
excretion is not the chief 
function of the sweat glands, 
for the perspiration is of 
great use to the body in help¬ 
ing to keep it from getting 
too hot, as w r ill be explained 
below. Each gland* opens on 
the surface of the skin by a 
pore. (Fig. 176.) 

Hygiene of the Skin.— 

Cleanliness requires frequent 
washing of the skin. There 
are removed from the skin 
dirt, disease germs, the solid 
parts dissolved in sweat, 
dead epidermal cells and oils. 

Soap should be used in washing, for soap dissolves oil by 
emulsifying it, as has been already described. 

Disease germs cannot easily get into the blood through the 
unbroken skin. Hookworm larvae on the bare feet of chil¬ 
dren get into the blood vessels of the dermis by way of the 
hair follicles. Lockjaw germs usually live in the soil, especi- 



Fig. 178.—Coiled end of sweat gland; 
the network of capillaries removed 
from its natural position around 
the coil. Compare with 5, Fig. 117 
and B, Fig. 176. 


*The number of sweat glands has been estimated at 2,500,000. 





232 


The Human Body'and Its Enemies. 


ally around horse lots, but may, if present on the skin, be driven 
into and under the skin with a nail (Fig. 257) or piece of fire¬ 
cracker, or a cap of a toy pistol, and a person may have lock¬ 
jaw and die. If you wound the skin and the blood runs freely 
and then dries nicely over the wound, remove the excess of 
blood with a dry clean cloth and tie the wound up without 
washing, for blood itself is a good cleanser. But if the wound 
is open, and dirt and bacteria are apt to get in, the wound 
should be washed with a disinfecting solution and bound up in 
a clean white cloth. 

Oftentimes you have noticed on the skin little tumors known 
as warts or moles. The warts are usually only temporary and 
harmless. The moles are usually harmless also, but may last 
a lifetime. Either mole or wart may degenerate or change into 
a dangerous tumor like a cancer, especially if it be in an ex¬ 
posed place where it is subject to irritation. For this reason 
these moles should not be allowed to become irritated. If they 
are in a place where irritation cannot be prevented, they 
should be thoroughly removed by a physician. Any sign of 
inflammation in a mole should be heeded, as it sometimes takes 
on a rapid growth. 

All young people are interested in having a good com¬ 
plexion, and without doubt pimples on the face are the com¬ 
monest cause of poor complexions. We do not know all of 
the facts as to the cause of these pimples, and until we do, 
we cannot do much toward preventing them. After the 
pimples appear, they are usually slow and stubborn to leave; 
but patience and care will drive them away. The prob¬ 
lem of how to get rid of them is too difficult to explain 
here, but it is best to make it a rule to do two things: 
first, get the entire body in as perfect health as possible, and, 
second, do not try any plans of cure except those recom¬ 
mended by people in whom you have confidence. 


Excretion. 


233 


Summary. 

The skin consists of a thin horny outer layer, the epidermis, 
and a thicker inner layer, the dermis. The dermis is richly 
supplied with blood vessels which supply the sweat glands and 
the growing cells of the epidermis, the hair and other organs 
of the skin. The functions of the skin may be summarized as 
follows: 

1. To form the covering for the body. (Both layers). 

2. To protect the more delicate parts (a) from injury; (b) 
from disease germs. (Epidermis, hair and nails.) 

3. To excrete waste. (Sweat glands.) 

4. To cool the body. (Sweat glands.) 

5. To act as the organ of touch. (Touch buds and nerves.) 

Questions. 

1. Why do the cells of the body form waste substances? 2. Name 
the two chief kinds of waste substances produced and the organs 
that remove them from the blood. 3. Why has the renal vein purer 
blood than the renal artery? 4. What cells in Fig. 174 take wastes 
out of the blood? 5. In what regard are the pocket and tubule (Fig. 
174) like glands shown in Fig. 117? 6. What are the functions of 
the skin? 7. Name the organs found in the skin. 8. What letters 
in Fig. 176 refer to the living cells of the epidermis? 9. Wherein do 
the dermis and epidermis differ? 10. With Fig. 176 before you, 
describe the skin. 11. Describe a hair. 12. Why do blood capilla¬ 
ries come close to the root of the hair? 13. To what part of a kid 
ney does SEG, Fig. 176, correspond? 14. Wherein are the tubule 
of a kidney and a sweat gland alike? 15. Why may warts or moles 
become dangerous? 16. How should we treat an open wound in the 
skin? 17. A closed wound, as a nail thrust? 


CHAPTER XXXIV. 


The Regulation of Heat in the Body. 


If you take the temperature of a healthy person with a 
thermometer, winter or summer, day or night, at rest or at 
work, you will find it alw.ays to be practically the same, about 
98 V 2 ' degrees Fahrenheit. How this engine, the human body, 
is kept from growing cold or getting too hot we shall discuss 
in this chapter. 

The cause of heat in the body has been touched on a number 
of times in this book. If not fully understood, reference should 
be made to the chapters dealing with oxidation, foods, respira¬ 
tion and kindred topics. This should be reviewed thoroughly. 

Distribution of Heat in the Body. —Exercising one part of the 
body causes all parts to be made warmer. For example, if you 
work the right arm forcibly on a warm day you will soon feel 
warm all over. If the extra amount of heat is produced only 
in the arm, why does the arm not become hot? Why do all 
parts of the body feel warmer? The blood distributes 
heat over the body, drawing it away from the part being exer¬ 
cised. So the blood carries away from the cells not only waste 
material, but also heat. 

It is now easy to answer the question, “What does the blood 
do with the heat brought away from the muscle cells?” The 
heat is carried to the skin, where the body comes in contact 
with the outside world. Here the heat leaves the body by 
radiation into the surrounding air. This occurs all the time, 
but faster in cold weather. In winter, therefore, more heat 
must be generated by oxidation; for that reason it is well to 


The Regulation op Heat in the Body. 


235 


eat more fats in the cold season. Alcohol will not do at all to 
produce heat in the body, as it is only partially oxidized, leav¬ 
ing the body through the lungs, skin and kidneys and injuring 
those organs as it goes. 

How the Body Gets Rid of Excessive Heat. —During exercise 
the body must use special means of getting rid of excessive 
heat. Note the color of the faces of boys and girls coming in 
after recess from a frolic on the playgrounds. Their faces are 
flushed because there is more blood in the skin. The blood 
brings the heat to the surface to be radiated away. This is 
brought about in the following manner: 

In all arteries, and so in those of the skin, there are muscles 
and nerves. When the muscles contract the artery is smaller 
and contains less blood. When they relax, the artery is dilated 
(made larger), and more blood rushes into the blood vessel. 
Heat stimulates the nerves that make the arteries expand. 
Therefore, when the body is warm the skin is red. 

In case there is much heat to be removed another thing hap¬ 
pens : the sweat glands begin to work faster, stimulated by the 
nerves and by the presence of warm blood around them. Sweat 
is poured onto the surface of the body, and there evaporates, 
carrying away much heat. For when water evaporates it 
absorbs heat, as can be seen by either of the following experi¬ 
ments : 

Experiments.— (1) Take two thermometers. Set one into a vessel 
of water. Around the bulb of the other tie a rag wet with -water out 
of the vessel in which the first thermometer is standing. Now fan 
the thermometers and note the drop in temperature of the one with 
the wet rag. (2) If the thermometers are not available, tie a dry 
handkerchief about one hand and a wet one about the other. Wave 
both through the air vigorously! Which feels the colder, and why? 
Tell why a person feels colder in wet than in dry clothes. 


236 


The Human Body and Its Enemies. 


In case of fever, the body becomes hot, partly because the 
sweat glands fail to do their duty. The temperature of the 
body in fever rises above 98 1-2 degrees Fahrenheit. 

How the Heat of the Body Is Retained. —We have just 
learned how the body gets rid of extra heat. In cold weather 
it is necessary to prevent loss of heat, for too low a tempera¬ 
ture is as dangerous to health as too high a temperature. 

If you recognize the fact that cold makes the arteries of the 
skin contract, you will readily understand Nature’s way of 
keeping necessary heat in the body: just the opposite way of 
getting rid of it, namely by driving the blood out of the skin 
into the body and away from the cold. The less blood brought 
to the skin, the less heat will radiate from it. 

Catching Colds. —But keeping the blood out of the skin is 
Nature’s safeguard only within limits. You must know that 
the skin is a large organ and may hold much blood. This is 
driven out of the skin by cold, and some of it causes conges¬ 
tion (crowding) of blood in the mucous membrane of the 
throat and other internal organs. Finally this mucous mem¬ 
brane of the air passages becomes inflamed -and bleeds from 
tiny hemorrhages. And if there are germs of cold or grippe 
present, they get a foothold in the body, causing disease. 
Without the germs one cannot catch cold, for travelers in the 
icy North do not have colds, since there are no sick persons to 
scatter germs. But, on the other hand, even if germs are pres¬ 
ent, without continued exposure, they are not likely to gain 
entrance into the blood. Sitting in a cold room below 65 de¬ 
grees Fahrenheit, or having on wet clothing, even if only on 
the feet, or too little clothing by day or covering by night, are 
all dangerous to health. 

Alcohol and Body Heat. —Alcohol is a drug that has the 
power of dilating the arteries of the skin, causing a rushing of 


The Regulation of Heat in the Body. 


237 


blood to the skin, as indicated by the red face of the drinker. 
This makes a person feel warm for a while, but it does not make 
him warm. It really makes him cool, for the presence of so 
much blood so near the surface of the body results in a rapid 
loss of heat by radiation. The feeling of warmth caused by the 
alcohol is a lie that alcohol tells the nerves. To 
take a drink of whiskey before venturing out into the cold is 
one of the worst things a person can do. 
found this out from experience long ago. 

Shelter. —Food and oxygen to make us 
warm, and well-trained blood vessels in the 
skin to regulate the heat are not sufficient for 
man: he needs also clothing and shelter. 

Man’s life is largely spent getting food, 
clothing and shelter. 

The rooms of our houses should not only 
be well ventilated but also kept at the right 
temperature, 65-75 degrees Fahrenheit. If a 
school room is heated and ventilated cor¬ 
rectly all parts of the room will be comfort¬ 
able ; none will be too hot or too cold, as is 
the case in too many schools in Texas as well as elsewhere. 
A room should also have moisture enough; this can be sup¬ 
plied by having a pan of water on the stove. The effects of 
sitting in a room that is too cold have been explained. If the 
room is too warm, the blood vessels of the skin become dilated, 
and on going into the cold, open air the body loses too much 
heat by rapid radiation. 

Clothing. —What animals do you see abroad in the winter 
time? Frogs? Snakes? Insects? You see only birds, covered 
with feathers; mammals, covered with hair; and man, who 
uses clothing to retain the heat of the body. In warm weather 


Arctic explorers 



Fig. 179.—Girl in 
summer clothing. 



238 


The Hitman Body and Its Enemies. 


clothing serves also to protect the body from injury and from 
the heat and light of the sun. 


Clothing depends for its power to retain heat on the fact 
that heat will not readily pass through dry air. Find out how 
an ice box (used to keep heat out) or a tireless cooker (used 
to keep heat in) are made, and you will learn how clothing 
keeps one warm. Furs have more air than hair. When a horse 
or a cow gets wet in winter it freezes much, for in that case 
water takes the place of air in their fur. Fur is the best ma¬ 
terial for clothing to keep one warm in extremely cold cli¬ 
mates. Of wool, silk, cotton and linen cloth, wool is the best 
for winter and linen for summer wear, for wool has the most 
and linen the least air in the meshes of the fibers. 
Clothing should not fit too tightly, for in that 
case circulation is cut off and the body’s heat can¬ 
not be well distributed. 

Clothing for the Climate of Texas. —In Texas 
a great many “northers” sweep down, causing 
sudden drops in temperature. When it becomes 
suddenly colder we should change clothing to suit 
the change in the weather. Many persons change 
to flannel or other kind of heavy underwear in 
the fall and wear this all winter, regardless of the 
weather. This is not the best plan to follow. It 
is best to have at least three weights of underwear 
to wear at different times. If one* is already wear¬ 
ing heavy underwear and the weather suddenly 
becomes colder he could double the underwear, using a light 
weight underneath a layer of heavy underwear. Some persons 
find that they catch cold in changing to light underwear in 
the spring, but this is usually due to the too great difference 
in the thickness of the underwear. A good rule to follow in 



Fig:. 180.— 
Girl in win¬ 
ter cloth¬ 
ing:. 


The Regulation of Heat in the Body. 


239 


changing from winter to summer underwear is to have a me¬ 
dium weight of winter underwear, or two thicknesses of sum¬ 
mer underwear, so as to make the change more gradually. 
These and many other rules of health that stand the test today, 
were well known to Benjamin Franklin, who was a keen ob¬ 
server as well as a great statesman. 

Our long hot summers can be made much more pleasant for 
us by wearing light, washable outer clothing. Suits of duck, 
cottonade, mohair and the like are light 
and cool, and when worn all summer 
enable us to endure the warmth of the 
climate better. It is to be noted also 
that light colored clothing is, in the 
sunshine, cooler than dark colored 
clothing of the same material. 

Bathing.—In your study of the skin 
you learned that various secretions are 
poured upon the surface of the skin by 
the sweat glands and the oil glands. 

You also learned that disease germs are 
likely to be present in dust and dirt that gather on the skin. 
From a standpoint of preventing disease, the fingers are of es¬ 
pecial importance and should be washed thoroughly with soap 
and rinsed off with clean water as often as the hands are 
soiled. Of course, all door knobs are soiled at all times, hence 
the fingers and hands should be washed well with soap before 
each meal. It is wise to keep the fingers from touching articles 
of food, even such as apples. The hands should always be 
washed after touching the body or clothing of anyone that is 
sick. Avoid using the common towel at public places; use the 
paper towel wherever supplied. (Fig. 181.) 

Up to this time most households are supplied with bath tubs 



Fig-. 181.—A paper towel 
is torn off, used and 
thrown away. 








240 


The Human Body and Its Enemies. 


instead of shower baths. This has been due to the fact that the 
advantages of the shower have not been realized, and also to 
the fact that home makers have not known a practical way to 
install a shower bath in an ordinary room with a pine floor. 
Fig. 182 shows a simple and cheap shower bath that can be 
substituted for a bath tub in an ordinary bath room. Under 

the shower is a porcelain basin and 
the water runs into this after trick¬ 
ling off the bather. A curtain is 
provided to keep the water from 
splashing on the wall or floor. This 
shower bath is more sanitary than 
the tub bath. 

Hot and Cold Baths. —Besides 
cleanliness, there are other effects of 
bathing, due to the temperature of the 
water. Cold baths are said to make 
a person feel energetic and should 
be taken in the morning; hot baths 
make a person feel sluggish and 
tired, and should be taken at bed¬ 
time, if at all. It is always unwise 
to take a bath soon after a meal or 
to bathe when one is tired. Those 
who play tennis or other games until 
they are almost exhausted and then take a bath will find that 
both the exercise and the bath do them more harm than good. 
In the morning, or after a nap in the afternoon, is about the 
best time to take a bath. 

Since people often go to extremes on the subject of bathing, 
a word of caution is necessary concerning the temperature of 
the bath water. It may be said that water about the tempera- 



Fig\ 182.—A shower bath is 
the most sanitary, because 
the water runs off of the 
body and away. 





















The Regulation of Heat in the Body. 


241 


ture of the body is always a safe temperature. Water should 
not be used much warmer than this unless for some special 
reason, and under the advice of a physician. The water may 
be cooler, or even quite cold, so long as it leaves a pleasant 
after-effect on the bather. This applies to those who are well 
and strong. No one who is at all sick should take cold baths 
except under the direction of a physician. It is not unusual 
to read in a newspaper that some man has been found dead 
in a bath tub. This shows that the bath has so much effect 
on anyone of delicate health that some judgment should be 
used in this matter. Nervous people who are weakly and dis¬ 
like the shock of the tub bath can get along about as w r ell 
with a sponge bath. 

Hot Applications. —The curative value of hot applications 

should be pointed out. When a person sprains an ankle or a 
wrist nature tries to cure the part by starting an inflamma¬ 
tion there; the part becomes hot and red. This is Nature’s 
way of rushing blood to the part to effect a cure. Wrists 
and ankles have few blood vessels in them, for there is not 
room for many. We can assist nature and help the circulation 
by applying hot cloths to the injured part. Whenever blood 
is wanted at a part of the body apply hot cloths; if there is 
a congestion, blood should be withdrawn by the application of 
cold water or ice to the congested part or heat to a distant part. 

Ventilation of the Bath Room.— Bath rooms should be venti¬ 
lated. When gas burners are used to heat the water great care 
should be taken to prevent suffocation from escaping gas. The 
heaters should have a hood and flue to carry off to the outside 
the carbon dioxide and other poisonous gases that result from 
the burning of fuel gas. 


242 


The Human Body and Its Enemies. 


Summary. 

The body is kept warm by the oxidation of the food and 
tissues. Fats are the best fuel food and are relished, in cold 
weather. Alcohol is doubly harmful in the cold. The body 
must be kept at a constant temperature of 98 1-2 degrees 
Fahrenheit. . Excessive heat is lost by radiation, which is 
greater when the amount of blood in the skin is greater, as 
during exercise or after drinking alcohol. Excessive amounts 
are removed by the evaporation of sweat. In cold weather the 
skin has less blood, and radiation is lessened. When the skin 
is cold for a long period one is likely to become sick with 
colds, grippe, etc. Further loss of heat is prevented by the 
use of extra clothing when out of doors, and by keeping the 
living rooms comfortable when remaining indoors. One should 
wear clothing to suit the climate and the weather. Bathing 
is necessary for cleanliness. Excessively hot or cold baths 
should be indulged in with judgment and only in case the 
after-effects prove to be agreeable. 

Questions. 

1. What are the functions of the skin? 2. How is bodily heat 
produced? 3. What becomes of the heat produced in a working 
muscle? 4. What is the effect of heat on the arteries of the skin? 
Of cold? 5. Is much or little heat lost when there is much blood 
in the skin? Why? 6. Why is the skin red when we are exercising? 
7. Why is the skin pale when cold? 8. Why does a person actually 
cool off faster after drinking alcohol? 9. What are the harmful 
effects of prolonged chilling of the skin? 10. Why is too warm a 
room harmful to a person? 11. Mention some helpful points with 
regard to clothing for Texas climate. 12. What is the best time to 
take a bath? 13. When should a person not take a bath? Why? 
14. Why is a shower bath more hygienic than a tub bath? 15. How 
would you treat a sprain? 


CHAPTER XXXV. 

Locomotion—Bones and Joints. 

There has already been occasion to refer to various tissues 
or collections of cells having particular duties to perform. Thus 
glands, mucous membrane, epidermis, are made largely of epi¬ 
thelial tissue. What are the shapes of the cells of this tissue? 
Muscle tissue is made of muscle fibers, long cells having the 
power to contract, thus producing motion. Muscle tissue is 
bound together by connective tissues to form a muscle. Wher¬ 
ever in the body a long, strong, flexible cord is needed it is 
made of connective tissue. Thus the valves of the heart and 
of the veins are made largely of connective tissue. Muscles 
are attached to bones by strands of connective tissue called 
tendons, and bones are bound to each other by similar strands 
called ligaments. Connective tissue is thus an important sup¬ 
porting tissue of the body. 

Cartilage tissue (or gristle), Fig. 136, has also been de¬ 
scribed. It is also a supporting tissue used for the framework 
of the trachea, wind-pipe and bronchi, the outer ear and the 
nose. Many bones have at their ends cartilage caps; for these 
caps must be smooth, so as to glide upon each other with little 
friction, and tough, so as not to break when struck together. 
Cartilage performs an important duty as a packing between 
the vertebrae of the backbone, for, being elastic, it helps 
deaden jars that might otherwise injure the brain. 

Observation Work.— (1) Secure a butcher’s specimen of the end of 
a muscle with the tendon still attached to the bone. Study all that 
can be made out from the specimen. Ligaments are best studied 
below with joints. (2) Measure your height accurately at bedtime; 
again on rising the following morning. What do the results prove 
about the cartilage between the vertebrae of the backbone? 


244 


The Human Body and Its Enemies. 


Uses of Bones.— With cartilage and connective tissue alone, 

however, the body would 
lack the support and rig¬ 
idity required. This sup¬ 
port is furnished to the 
body by means of bones, 
two hundred six in 
number, of many shapes 
and sizes, all fastened to¬ 
gether into a system called 
the skeleton. (Fig. 183.) 
The skeleton gives the 
general shape to the body. 
With muscles fastened to 
this and all covered by the 
skin, the shape of the 
body is completed. 

Bones act as organs of 
support in two special 
ways. The most vital or¬ 
gans of the body (most 
of the sepcial organs we 
have studied) are located 
in cavities inside the body 
whereby they are protect¬ 
ed by bony boxes. The 
skull is such a box, with 
its flat bones ‘ ‘ dove¬ 
tailed ’ ’ toget her into 
tight joints. (Fig. 80.) 
The spinal cord lies in a tube made by hollows of the verte¬ 
brae. (Fig. 184.) The patella, or knee-cap, protects the deli- 



Fig. 183.—The human skeleton. 






Locomotion—Bones and Joints. 


245 


cate knee joint from injury. The heart and lungs are located 
in the chest. Such protecting bones are mainly flat bones 
with red marrow, as you can see by studying, for example, 
the sawed end of a rib secured from the butcher. This red 
marrow is of special interest be¬ 
cause therein are manufactured 
most of the red corpuscles. There 
are, however, many flat or irregu¬ 
lar bones with red marrow that 
serve other purposes than for pro¬ 
tection ; for example, the shoulder 
blades and the hip bones. 

Besides serving as support to the 
body, bones are used as levers in 
connection with muscles to give mo¬ 
tion to parts of the body. Many flat 
bones are movable to some extent, 
the lower jaw and the shoulder 
blade being good examples. The ver¬ 
tebrae may move upon each other 
slightly, enabling us to lean the body 
in any direction. The bones of the hand and wrist are short 
and irregular bones, with red marrow, and, of course, are 
movable. But for rapid and powerful motion there are certain 
long bones of the limbs (Fig. 183 and Fig. 185) with their mus¬ 
cles to move them. These are light, being hollow, and of suf¬ 
ficient thickness to do their work. The femur or thigh bone 
is an example of such a long bone. It is enlarged at both 
ends, where it joins other bones, and has projections to which 
muscles are attached. Inside, the enlarged end of the bone 
has a spongy appearance, that is, it is full of hollows irregu¬ 
larly scattered among the bone tissue. (ST., Fig. 189.) But 



Fig. 184.—Three vertebrae 
with portion of spinal cord 
in place. FR, hollows for 
attachment of ribs; FV, 
surface for attachment of 
next lower vertebra. 





246 


The Human Bod y and Its Enemies. 


the long, smooth stretch of bone between the enlarged ends, 
the shaft, consists of compact tissue, with a continuous hol¬ 
low, the marrow cavity (Fig. 189), filled with a fatty marrow. 

Joints. —The place where two bones are joined together is 
called a joint. Some joints, as those of the skull or that be¬ 
tween the sacrum and the innom¬ 
inate bones at the pelvis are im¬ 
movable. The vertebrae are very 
slightly movable, one upon the 
other, by the compression of the 
elastic cartilages between them. 
The bones of the wrist and ankle 
glide over one another; their 
joints are therefore called glid¬ 
ing joints. The elbow and the 
knee joints allow a greater free¬ 
dom of motion to the arms and 
the legs, which move like a hinged 
door; they are called hinge joints 
(Fig. 198). Still greater freedom 
of motion is enjoyed by the upper 
arm, which is attached to the 
shoulder blade by a ball and sock¬ 
et joint, allowing the arm to be 
moved in almost any direction. 
By a similar joint, but by a deep¬ 
er socket, the femur is attached to the innominate or hip bone. 
At the elbow there are two joints: the ulna is attached to the 
humerus by a hinge joint, the radius by a pivot joint, which 
allows the latter bone to twist around and enables us to turn 
the hand palm up or palm down (Fig. i85), in a way in which 
we cannot turn the foot. Study other joints in your own 



Fig. 185.—Diagrams, showing 
how the hand may be turned 
around by means of the pivot 
joint of the radius. For use 
of hinge joint see Fig. 193. 






Locomotion^-Bones and Joints. 


247 


body and try to tell what kind of joint each is. A joint is a 
wonderful piece of mechanism. Cartilage covers the en¬ 
larged end of the bone, thus affording a smooth surface. 
To reduce friction still further, there is in the joint a two¬ 
layered membrane (the synovium), which secretes a fluid 
that keeps the joint w r ell oiled. (Compare the synovium 


FIG. 186. FIG. 187. FIG. 188. 



Fig. 186.—Hip joint; I, innominate bone; CL, capsular ligament. 

Fig. 187.—Hip joint with capsular ligament (CL) cut to show the round 
ligament (RL). 

Fig. 188.—Section of hip joint. CL and RL, ligaments; S, synovial mem¬ 
brane over cartilage of joint; SF, synovial fluid. 

with the plurae and the pericardium.) The ball and socket 
joint is described in Figs. 186-188. There are two liga¬ 
ments, the round ligament (RL) and the capsular ligament. 
(CL.) Further details of the joint can be studied in these 
pictures, and also in an actual joint of some animal. 




248 The Human Body and Its Enemies. 

Observation Work.—Secure a ball and socket from the butcher, 
first having him saw it in two lengthwise. Study the compact and 
the spongy parts of the bones, the smooth cartilage tip of the “ball” 
and the lining of the socket and the ligament. 

Hygiene of Joints. —Sometimes a joint becomes dislocated 
or sprained, ligaments being torn loose or strained. Hot ap- 


FIG. 189. 
WtAD 


FIG. 190. 



Fig. 189.—Femur, one-half in longitudinal section, showing 
spongy tissue (ST) in end and compact tissue around the 
marrow cavity in shaft. P, periosteum. Cut end. A, 
enlarged in Fig. 190. 

Fig. 190.—End A of Fig. 189 enlarged, showing bone tissue 
in shaft of femur. 

Fig. 191.—Bone tissue, block B of Fig. 190, still more en¬ 
larged. This shows the arrangement of bone cells (black 
dots) about the canals. Still finer canals run out from 
the cells. 


plications to the sprained spot will aid nature to effect a cure. 
A severe sprain should receive the immediate attention of a 
physician. 


Bone Tissue. —If you hold in your hand a cross section of 
a long bone, such as appears in the center of a piece of round 
























Locomotion—Bones and Joints. 


249 


steak, the bone tissue seems perfectly solid and impenetrable. 
Under the microscope, however, it is quite different. The 
apparently solid part of the bone is seen to be traversed by 
fine canals containing blood vessels and nerves, and about 
these canals living bone cells are arranged as 
shown in Figs. 190 and 191. The cells themselves 
are connected with the canals and with one an¬ 
other by still finer tubes. Thus it is seen that 
even the solid part of bone is porous and sup¬ 
plied with blood. Figs. 189-191 should be care¬ 
fully studied to make this point clear. Poisons, 
like alcohol and tobacco, are carried out into the 
bone canals to the very cells. This helps to ex¬ 
plain why youthful users of these drugs become 
stunted in growth and fail to attain the full de¬ 
velopment of their bones and other organs of 
their bodies. 

All bones are surrounded by the periosteum 
(P), which holds many blood vessels and nerves 
that pass through it on their way into the bone. 



Fi 


192. - 
Bone tied 
into a knot 


Experiments to Show the Composition of Bones.— (1) Examine a 
bone that has been burned thoroughly. Describe it. Compare it 
with pieces of limestone. It is the mineral part of the bone, made 
up largely of limestone and phosphate of lime. It. is the part that 
makes bone hard. (2) Soak a bone of convenient size, say a chicken 
“drumstick,” in strong vinegar or weak hydrochloric acid, and note 
the result. Tie the bone into a knot (Fig. 192). State what has 
been removed from the bone. What is left is “animal matter,” 
which gives toughness and a certain amount of elasticity or “spring¬ 
iness” to the bones. 

Hygiene of Bones. —It is of extreme importance that 
people recognize the fact that children’s bones contain a small 


250 


The Human Body and Its Enemies. 


proportion of mineral matter, and are, therefore soft and flex¬ 
ible. Since this is true, it is easy to see that children’s bones 
are easily bent out of shape and permanently deformed. A 
babe may bend his legs out of shape by learning to walk too 


FIG. 193. FIG. 194. 



Fig-. 193.—A deformed foot. 

Fig-. 194.—Natural shape of foot and 
shape of ill-fitting- shoe. 


early, or by walking too 
much. It is important for 
old and young, but especially 
for the young, to assume an 
erect posture in both sitting 
and walking, with chest 
raised and shoulders thrown 
back. This is not only bet¬ 
ter for the bones but for the 
lungs and other organs,, and 
it also improves one’s per¬ 
sonal appearance. Many per¬ 
sons are one-sided from al¬ 
ways carrying articles 
(school books, for example,) 
on the same side. 


Observation Work.—Measure carefully the height of each shoul¬ 
der from the ground. Compare the two measurements to find out 
whether or not you are one-sided. 


Tight clothing is especially to be condemned as unhygienic. 
The habit of tightly lacing the waist is very common, and is 
fraught with great danger to the health. 'The feet, too, are 
often abused with tight and ill-shaped shoes. Shoes should 
fit well and should not have high heels. There are three 
ways by which the skeleton helps to prevent the jarring of the 
brain: the elastic cartilages between the vertebrae, the curva¬ 
ture of the spinal column and the arched foot. (Fig. 195.) 







Locomotion—Bones and Joints. 


251 


The foot naturally acts like 
But with high heels the foot 
of the shoe, pinching the foot 
still more and causing corns 
and other painful ailments. 

School Desks. —Inasmuch 
as young people spend a 
great deal, of their time sit¬ 
ting at their desks in school, 
it is essential to their health 
that they learn to assume 


i spring in deadening the shock, 
tends to slide down into the toe 



Fig:. 195.—Bones of foot, to show 
arched shape. 


a correct posture and get in¬ 
to the habit of so doing. 
This is, of course, impossible 
where the desk is too high 
or the seat too low. School 
boards and school patrons 
do not always understand 
that it is important that 
desks be hygienic and that 
they be of the right size and 
shape to suit the pupils. If 
the seat is too low the posi¬ 
tion of the occupant is nec¬ 
essarily cramped. If it is too high, the feet dangle in the air, 
the pressure on the muscles of the thigh cuts off the circula¬ 
tion and the weight of the feet bends the femur out of shape. 
If the desk is too high the arm and shoulders are unduly 
raised in writing; if too low, stooping is necessary in working 
over the desk, and round shoulders and hollow chests result. 
Many schools are thus causing physical defects in children— 
defects that often persist through life. The ideal school desk 



Fig-. 196.—A school desk and seat ad¬ 
justable to size of pupil. 





252 


The Human Body and Its Enemies. 


is the adjustable desk. (Fig. 196.) The next best is the patent 
desk of the right height to suit the child. It is the duty of 
taxpayers and school trustees to see to it that these desks are 
secured. But if this is not done, the teacher can often make 
a child comfortable with a box as a foot rest or with some 
other device, or she can relieve the situation, particularly with 
the youngest children, by giving frequent short recesses and 
by dismissing early in the afternoon. 

Summary. 

Bones with connective tissue and cartilage form the frame¬ 
work of the body. Bones also protect delicate organs from 
injury, and, having muscles attached to them, act as levers to 
move the body. These two hundred or more bones of the body 
are of many different shapes, according to the function they 
perform. The long bones are hollow, so as to combine strength 
with lightness of weight. The flat bones contain “red mar¬ 
row,” where the red corpuscles are manufactured. Even the 
solid part of the bone is porous, being traversed by fine canals 
containing blood vessels and nerves. The bone cells are ar¬ 
ranged around the canals within the bone substance. Bone 
tissue contains animal matter for toughness, and mineral mat¬ 
ter for firmness. 

Bones are bound together by ligaments at the joints. Smooth 
cartilages and synovial fluid in the joint prevent friction as 
the bones rub upon each other. 

Mineral matter is deposited in bones throughout life. The 
bones of children are soft and therefore easily bent out of 
shape. Correct positions in sitting and standing and avoid¬ 
ance of tight clothing are essential to the proper growth of 
the bones. Anything that injures the body in general, like 


Locomotion—Bones and Joints. 


253 


alcohol, tobacco or unhygienic habits, will prevent the proper 
development of the bones. 

Questions. 

1. Name some organs of which cartilage tissue forms a part. 2. 
What is a tendon? 3. A ligament? 4. Point out each in two dif¬ 
ferent pictures. 5. Of what kind of tissue are tendons and liga¬ 
ments chiefly composed? 6. In what direction do the canals run 
through a long bone? 7. What are the canals for? 8. How are 
the bone cells arranged with reference to the canals? 9. With Figs. 
189-191 before you, describe bone tissue. 10. State the use of bones. 
11. Give the chief uses of each bone that may easily be seen in Fig. 
183. 12. Name the kinds of joints and give examples. 13. Name 

the two joints in the elbow. 14. State the use of each. (Study 
Figs. 185 and 198.) 15. How may tobacco keep the bones from 

developing properly? 16. How can we prove that bones contain 
mineral matter? 17. Animal matter? 18. Why may children’s bones 
be easily bent out of shape? 19. How may you develop an erect, 
strong framework of your body? 20. State the importance of hav¬ 
ing the right kind and size of school desk. 


CHAPTER XXXVI. 


Locomotion : Muscles. 



Fig-. 197.—The muscles. 

passage of food from the stomach. A 


When a boy is large 
in stature his size is 
due mainly to the size 
of his bones; it is his 
muscles that give him 
power to do things. 
When a boy wishes to 
show his strength he 
holds out his arm and 
says, “Feel my mus¬ 
cle.” If the biceps of 
his arm is large and 
hard, he has strength, 
for the muscles can con¬ 
tract with much power. 

Uses of Muscles.— 
Throughout this book 
reference has been 
made to the chief use of 
the muscles, namely to 
produce motion. Mus¬ 
cles are used in the di¬ 
gestion of food. The 
pylorus is a sphincter 
muscle whose special 
use is to regulate the 
large number of muscles 




Locomotion: Muscles. 


255 


are used in breathing. The tongue itself is a mass of mus¬ 
cles. We noted that the heart is a muscular sac, the use of 
which is to pump blood, and that the arteries and veins con 
tain muscles. As long as we live there must be some motion 
of organs in the body. For the larger motions of the body, 
muscles are attached to bones. A muscle runs from bone to 
bone across the joint, and thus, by contraction moves one 
bone at an angle upon the other. (See Fig. 198.) In this way 
the fingers, arms, legs, etc., are moved and the whole body is 
carried from place to 
place, as in walking, run¬ 
ning and jumping. Even 
in standing many muscles 
are in use. (Fig. 199.) 

About two-fifths of the 
\veight of the body, or 
more than one-half of the 
soft parts of the body 
consists of muscle. (Fig. 

197.) An inspection of a 
butcher’s shop will con¬ 
vince one of the amount 
of muscle it takes to carry on the work of an animal’s body. 

While it is true that muscles are of use primarily for move¬ 
ment, they serve other purposes. The muscles of the abdomi¬ 
nal wall protect the intestines, and the cheek forms one of the 
boundary walls of the mouth. Muscles, too, with the skeleton 
as the support and with the skin as a covering give grace of 
form to the body; they cover the joints and fill the cavities. 

Two Kinds of Muscles. —A little reflection and experiment 
will show that there are two kinds of muscles. You can move 



Fig. 198.—Muscles are attached to bones 
for the larger motions of the body. 




256 


The Human Body and Its Enemies. 


your finger, your eyelids, your arm, at will. But you cannot 
make your heart beat, nor stomach churn, and after you have 
pushed food back into your throat you cannot stop it from 
going down the gullet. There must therefore 
be two kinds of muscles according to whether 
they are under the control of the will or not. 
The muscles used in the large movements of 
the body, as of the limbs, are under the con¬ 
trol of the will and are called voluntary mus¬ 
cles. Muscles not under the control of the will 
are called involuntary. Locate some involun¬ 
tary muscles. 

There is, too, a great difference in the cells 
of the two kinds of muscles, as shown in Fig. 
200. The cells are all long and are for that 
reason called fibers. The voluntary muscle 
cells are striped crosswise (I), and have many 
nuclei; the involuntary muscle cells are smooth 
and spindle-shaped, and have one nucleus each 
(III). The striped muscle fibers have to con¬ 
tract quickly and forcefully; the smooth fibers 
are slow-acting. The heart muscles are there¬ 
fore an exception, in being involuntary but 
striped (II), for the contraction of the heart 
must be rapid like that of the limb muscles. 

Structure of a Muscle. —Muscle fibers are 
connected together into a whole organ, a mus¬ 
cle, with connective tissue fibers, which extend 
all through a muscle and come out at the ends 
(Fig. 201.) The nearer the end of the muscle, 
a piece of beefsteak is cut the tougher the 
the connective tissue is more plentiful than 


Fig. 199. — The 
large muscles 
us *d in stand¬ 
ing. 


as the tendon, 
therefore, that 
steak, because 








Locomotion: Muscles. 


257 


muscle tissue. (Fig. 81.) The function of the tendon is to bind 
muscles to bones. Often the bone that is to be moved is some 



Fig - . 200. Muscle fibers: 1, striped, voluntary; II, striped of heart; III, 
smooth. C, connective tissue; A, cut ends cf fibrils, better shown at 
F; P, process of heart muscle fibers. S, a single smooth muscle cell. 

distance from 
the muscle that 
moves it; the 
tendons, there¬ 
fore, serve to 
bridge over a 
part where 
there is insuffi¬ 
cient room for 
muscles. 

Observation Work 

Study your fore¬ 
arm, hand and 
fingers for the 
parts menti on e d 
above. Move your 
fingers freely and 
at the same time 
watch all parts of 
muscles, tendons, bones, etc. 


FIG. 201. FIG. 202. FIG. 203 



Fig. 201 to 203.—Structure of a muscle. 

Fig. 201.—Biceps muscle of arm, with portion cut 
away exposing the bone (H). Fig. 202. Lower 
portion of Fig. 201 more enlarged, showing the 
larger bundles; F, smaller bundles within larger 
bundle. Fig 203, a smaller bundle containing mus¬ 
cle fibers (MF) bound together by connective tis¬ 
sue (C). 

the arm and hand to determine the relation of 









































258 


The Human Body and Its Enemies. 


Hygiene of the Muscles. —Review page 131 and then state in 
your own words whence the muscles secure the energy with 
which to do work. 

Food must necessarily be brought to the muscles to repair 
them as they are used and to furnish them with energy. Blood 
vessels course through the muscles, and the 
blood capillaries come close to the fibers or 
cells as they do to all of the cells of the 
body. (Fig. 204.) This is, of course, as you 
would expect from what you have already 
learned about the relation of capillaries and 
cells. To nourish the muscles properly food 
must be taken in well-balanced rations. 
What would you suggest as a model dinner 
for an athlete training for a contest ? Greasy 
foods and pastry are not eaten by the best 
athletes. 

Alcohol and tobacco are also strictly 
avoided by athletes, for they have uniformly 
found these drugs to reduce their strength. 
If neither of these poisons is good for an 
athlete, does it not seem reasonable to sup¬ 
pose that they are harmful to all who use 
them? If a boy will abstain from the drugs 
to Win a footrace or help win a football game, does it not pay 
to do without them so as to have a healthy body for the battles 
of life? Some persons believe that they can do harder work 
under the stimulus of alcohol; but they are deluded in this, 
for experiment after experiment has proved that alcohol ac¬ 
tually lessens the power of the muscles to contract. This is 
another fact which Benjamin Franklin knew from observa¬ 
tion, and which was later proved by scientific experiment. 



Fig-. 204. Blood ca¬ 
pillaries supply¬ 
ing muscle fibers. 








Locomotion: Muscles. 


259 


Fresh air, rich in oxygen, is another essential to the health 
of the muscles, as it is to the health of the whole body. 

Exercise is absolutely essential to the health of the muscles. 
Its most important advantage is the effect on the circulation 
of the blood and lymph, as described in Chapter XXXII. The 
heart is made to beat faster, and is thus itself exercised; the 
breathing movements are increased; the veins are squeezed 
with each contraction of a muscle, and the blood, directed by 
the valves, is forced on toward the heart. All of these ac¬ 
tivities help the circulation of the blood and the lymph. 

To be of greatest value to the body, exercise must be pleas¬ 
ant. Play is, therefore, an essential element in one's training. 
All young animals play; it is Nature’s way of developing their 
muscles. Children should be allowed their God-given right 
to a reasonable amount of play. Games, moreover, develop 
the social instinct, teach children to work together (“team 
work”), to be honest, to 
be considerate of one an¬ 
other, to stand up for 
one’s rights, and to learn 
human nature. Older per¬ 
sons should engage in 
outdoor sports as stren- pjg 205 ^ healthful form of recreation, 
nous as circumstances 

will allow. Name ten good games that require some exercise 
out of doors. 

Gymnastic exercises are valuable principally for the fact that 
with them deformities may be corrected or undeveloped mus¬ 
cles brought out. Exercises for almost every voluntary mus¬ 
cle of the body have been invented, so that a person may take 
a scientific course in physical culture by the gymnastic method. 
Gymnastic exercises usually lack interest, and are, in general, 




260 


The Human Body and Its Enemies. 


not so good as enjoyable games. A five or ten-minute 
drill, with movement of the trunk and limbs, may, however, 
be very beneficial in school, where the pupils have to sit still 
so long at a time. A five-minute walk out into the open air 

would be bet¬ 
ter, but the 
weather fre¬ 
quently pre¬ 
vents this. 

Boys and 
girls need a 
great deal of 
play, but also 
an equal 
amo u n t o f 
good h ard 
work. A good 
combinati o n 
would be 

splitting wood, digging bait and going fishing. Some hard 
work is good for girls, too, for example, sweeping (but not 
by the dry method) and washing dishes; but, they, too, need 
an equal amount of play. 

Fatigue. —There is a limit to the amount of exercise one 
ought to take. Have you ever been out on a picnic or a 
day’s tramp and come home very tired? And did you 
not feel “sore” the next day, the very muscles hurting when 
you touched them? Why did they hurt? Study Fig. 152 and 
try to tell the answers. Waste products from the muscle cells 
themselves accumulate during continued heavy exercise faster 
than they can be carried off by the blood, and they act as a 
toxin on the cells of the body. This condition is called fatigue. 



Fig-. 206.—A playground is a valuable part of a school 
equipment. 



































Locomotion: Muscles. 


261 


Rest.— Rest, therefore, becomes imperative. Rest gives the 
muscle and nerve cells a chance to get rid of waste substances 
and to rebuild worn-out protoplasm. During rest the building- 
up process is greater than that of the tearing-down. A per¬ 
son who does not rest sufficiently cannot do his best work, 
does not enjoy life fully and may finally become a prey to 
disease germs. 


Summary. 

Muscles, by contraction, cause all motion of the body. Some 
muscles are involuntary and are made up of smooth muscle 
fibers. Such muscles carry on the movement of the internal 
organs. The voluntary muscles, made of striped fibers, are 
attached to bones, and with them as levers, move the limbs. 
Blood capillaries supply all of the muscle fibers with food and 
oxygen, and carry away wastes produced in exercise. They also 
carry alcohol and the poisons of tobacco to the fibers, weak¬ 
ening the muscles. 

Exercise is highly beneficial to the muscles if pleasant and 
enjoyable. Outdoor games are the best form of exercise, ex¬ 
cept for special purposes. We should never exercise to the 
point of bing “dead tired,” but should stop and rest when 
the point of pleasant fatigue is reached. 

Questions. 

1. State the use of muscles. 2. Point to the biceps and the tri¬ 
ceps muscles of your arm. 3. Place your biceps in position B, Fig. 
198. 4. What joint does the lower tendon of the biceps cross? 5.. 

Name an organ that contains muscles of the smooth kind only. 6. 
Describe three kinds of muscle fibers. 7. How do the muscle cells 
secure their nourishment (Fig. 204)? 8. Comparing Fig. 204 with Fig. 


262 


The Human Body and Its Enemies. 


152, discuss the general activities of a muscle cell. 9. What part does 
connective tissue play in a muscle (C, Fig. 203)? 10. What part of 

Fig. 202 is the bundle shown enlarged in Fig. 203? 11. What are 

some of the needs of muscle cells (Fig. 152) ? 12. What drugs weaken 

the muscles? 13. Discuss the value of exercise to the muscles. 14. 
What is the chief value of play? 15. Discuss the use of gymnas¬ 
tics. 16. Why is rest necessary? 17. How is fatigue produced? 


CHAPTER XXXVII. 


The Nervous System — General. 

Thus far we have considered the body as being made up of 
myriads of separate cells, each with its own work to perform. 
These cells are united to form tissues, and tissues make up or¬ 
gans. Thus a gland is an organ made up mainly of epithelial 
tissue, each cell of which does its part of the work of the 
gland. We have considered the different organs chiefly as 
separate parts of the body without especially noticing how 
one part acts upon another. We have studied the operation or 
work of the cells, tissues and organs. In the present chapter 
we shall lay stress on the co-operation or working together of 
the parts of the body. 

Examples of Co-operation. —Everyone is familiar with ex¬ 
amples of the co-operation of the organs for the good of the 
whole body. The blood serves every cell in a very important 
way, as has often been pointed out. The liver does work of 
value to the whole body, for if it were removed death would 
result. Even waste substances in small amounts are of value 
to the body, because they cause fatigue and induce sleep. When 
we consider the body as made up of many co-operating parts 
we might liken it to a perfect baseball team, each of whose 
nine members does the right thing at the right time, all co¬ 
operating that the team may win. 

Review Work.—Make a list of the most important organs you have 
studied and state what each does for the good of the whole body. 

The more you think about it the more you will realize how 
beautifully this machine, the body, works. If some one 


264 


The Human Body and Its Enemies. 



Eigr. 207. The nervous system. 


strikes at you, you wink 
your eyes, throw up your 
hands and perhaps step 
back. If a particle of food 
goes “the w r rong way” on 
passing the throat (see Fig. 
133) you cough; or if dust 
enters the nose, you sneeze. 
As you taste food and begin 
to chew, the digestive glands 
begin to secrete. 

If you prick your finger 
with a pin there is a mes¬ 
sage sent to the brain and 
spinal cord, and in an in¬ 
stant a message is sent back 
to the proper muscle to re¬ 
move the finger from the 
place of danger. Or, I may 
say, “Move your right 
thumb; ’ ’ you hear what I 
say and do as I request. 
My voice, your ear your 
thumb—nature has, in a 
wonder f u 1 w a y, made 
means of communication 
among them. 


Review Work.—Review pages 131 and 259 and tell at least a half 
dozen things that happen in as many of the organs of the body when 
you begin to exercise, for instance, to run. Review Chapter XXXIV 
and tell how heat and cold affect the blood vessels of the skin. 

Nerve Cells. —Communication between parts of the body is 


The Nervous System—General. 


265 


brought about by nerves, as every one knows. It is hardly 
necessary to state that the nervous system is made up of cells 
as is every other part of the body. A little reflection would 
lead us to suppose, which is actually the case, that 
nerve cells are longer and more slender than any 
other cells, even than muscle and connective tis¬ 
sue fibers. Fig. 208 is a diagram of a nerve cell. 

The body of the cell (called simply nerve cell 
for the sake of brevity) contains the nucleus and 
has running off from it one or more long pro¬ 
cesses and usually many short ones. The short 
processes are of use in communicating with ad¬ 
joining cells; the long ones, the nerve fibers, run 
to the various cells of the body or to other nerve 
cells. The nerve fibers may be very long, these 
running into the feet attaining the length of a 
yard or more. A single nerve fiber cannot be 
seen by the naked eye, but when many are bun¬ 
dled together they form a nerve, and a nerve can 
be seen as a white strand of greater or less thick¬ 
ness. 

The Function of Nerves. —If you were asked 
what the brain is for, you would probably say, “To know and 
feel with,” by which you would mean that the brain is the 
organ of the mind. If asked the function of nerves you would 
now readily answer that nerves carry impulses from one part 
of the body to another, and so keep the parts co-operating 
for the good of the whole. These two answers are as nearly 
correct as most people can state them. We might compare 
our system of nerves with a telephone system. The nerves cor¬ 
respond to the wires which connect homes, stores and offices 
in a city. There are, moreover, nerve centers, the brain and 




Fig. 208.—A 
nerve cell. 




266 


The Human Body and Its Enemies. 


the spinal cord, corresponding to the central office or exchange 
of the telephone system. When you wish to telephone, you 
first “call central,” and give the number you want. Like¬ 
wise, when you touch the point of a pin with your finger, a 
“call” is sent to the “central” of the body. Again, the cen¬ 
tral operator of the telephone gives you the number you call 
for and rings that number. So, too, in the brain or spinal cord, 
the message, “Sharp object at finger,” is changed to “Move 
finger away,” and this message is sent to the proper muscles 
of the arm and hand. There are, therefore, nerves running in 
from the skin, which bring us in touch with the outside; and 
there are nerves running out to the muscles, controlling their 
action. 

The organs of the nervous system might be said to consist 
of the central nervous system, the brain and the spinal cord, 
containing most of the nerve cells; and the peripheral nervous 
system, consisting of nerves and containing mainly nerve 
fibers. 

Summary. 

The functions of the nervous system are to act as the organ 
of the mind and to control all the organs of the body. The 
nerve cells receive or send on impulses or messages, and their 
nerve fibers carry the impulses from one part of the body to 
another. 

Questions. 

1. Do you think the various parts of the body are independent 
of one another? 2. Give reasons for your answer. 3. Give examples 
of co-operation of organs. 4. How are parts brought into communi¬ 
cation? 5. Wherein is the nervous system like a telephone sys¬ 
tem? 6. Name the parts of the central nervous system. 7. Of what 
does the peripheral nervous system consist? 8. Find these parts 
on Fig. 207. 


CHAPTER XXXVIII. 


The Brain. 


(OH VOLUTIONS 
CEREBRUM 


Since the brain plays such an important part in the body 
it might be pointed out as the most important organ of the 
nervous system. We must bear in mind, however, that all of 
the parts of the nervous system are of importance. The 
organs of the nervous 
system are: 

1. The brain (Fig. 

209). 

2. Twelve pairs of 
nerves arising from the 
brain and running out 
mainly to the head, 
shoulders and vital or¬ 
gans (Fig. 210). 

3. The spinal cord 
(Fig. 210). 

4. Thirty-one pairs 
of nerves arising from 
the spinal cord and 
sending out branches 
into the trunk and the 
limbs (Fig. 210). 

5. The sympathetic ganglia and their nerves (Fig. 210). 1 
and 3 make up the central nervous system; 2 and 4 the peri¬ 
pheral nervous system. 



cerebellum 


MEDULLA 


Fig. 209. 


The brain and upper part of the 
Spinal cord. 










268 


The Human Body and Its Enemies. 


The brain lies in the hollow of the skull, and the spinal cord 
in the canal running through the spinal column. (Figs. 79 and 
207.) Besides the bony covering, both have three double pro¬ 
tective coverings,* with all the spaces filled with lymph. So 
the brain and cord fit snugly into their cavities. The brain is 
also protected from jars by the springy arch of the foot, by 
the curves of the backbone and by the cushions of cartilage 
between vertebrae. 

The Cranial Nerves —Coming off from the brain are bundles 

of nerve fibers. There are 
twelve pairs, called cra¬ 
nial nerves, that go to the 
head, shoulders and vital 
organs of the chest and 
abdomen; tlies e pass 
through openings in the 
skull. One pair of these 
(Fig. 210) goes to the 
nose, and they are called 
the nerves of smell; an¬ 
other (2) to the eyes, as 
the nerves of sight; and 
one pair (8) to the ears, 
as the nerves of hearing. 
Three pairs (3, 4, 6) 

cause the eyeballs to 
move. Toothache, taste and other sensations pass up other 


♦The three together are called the meninges. (M., Fig 217.) 
The disease of the nervous system called eerebro-spinal meningitis 
derives its name from these membranes, which are influenced by 
the disease. 









The Brain. 


209 


cranial nerves to the brain; when you laugh or cry the brain 
sends its commands along certain other nerves to the muscles 


of the face. The cranial nerve (10) going to the chest and ab¬ 


domen has to do 
with the heart-beat, 
breathing and other 
vital processes. Other 
nerve fibers in large 
numbers le a d i n g 
from the brain pass 
into the spinal cord. 



Fig. 211. Section of a por- Fig. 212. Section of 
tion of the brain; gray spinal cord; gray 
matter near the sur- matter on the in¬ 
face. side. 



Fig. 213. The brain from above; only 
the cerebrum is seen. 


the brain the gray matter i 


Ganglia. —The nerve cells 
are all contained in certain 
definite parts of the brain 
and spinal cord, and in cer¬ 
tain small collections of 
nerve cells called, ganglia,* 
that also have a definite lo¬ 
cation not far from the cen¬ 
tral nervous system. One 
region of the brain and of 
the spinal cord is, then, com¬ 
posed mainly of nerve cells, 
and this is called gray mat¬ 
ter (from its appearance in 
section). The region of fibers 
is called white matter. In 
on the outer surface, and 


* A ganglion is simply a collection of nerve cells. The brain and 
spinal cord may be considered enormous ganglia. 




270 


The Human Body and Its Enemies. 


forms the cortex of the brain (Fig. 211) ; in the spinal cord 
the gray matter is on the inside. (Fig. 212.) 

The brain consists of three main parts: the cerebrum, the 
cerebellum and the medulla." 

The cerebrum consists of two halves, the cerebral hemis¬ 
pheres (Fig. 213), connected by a mass of fibers. In a man it 
is the largest organ of the nervous system, though this is not 
the case in some of the lower animals, for the higher the ani¬ 
mal the larger the cerebrum. The larger the organ is, the 
more nerve cells it may contain, since the larger size increases 

the extent of the 
cortex or gray mat¬ 
ter. In man and in 
several of the more 
intelligent 'animals, 
like the dog and 
horse, the cortex is 
further increased by 
folds or convolu¬ 
tions. (Figs. 213 and 
215.) A great num¬ 
ber of fibers connect 
the different parts 
of each hemisphere of the cerebrum (Fig. 214), connect the 
hemispheres with each other, and run out from the cells to 
the spinal cord and to various parts of the body. Those fibers 
passing from the cerebrum into the spinal cord cross in the 
medulla; so that if the left side of the brain were injured, the 
right side of the body (except the head) would be paralyzed. 

The cerebrum is the organ of the mind. Without it we could 



Fig. 214. Nerve fibers connect the parts of the 
cerebral cortex with one another. 


*The medulla oblongata is also called the “bulb.” 







The Brain. 


271 


not know, think, imagine, remember or do anything which 
we commonly associate with the activities of the mind. In cer¬ 
tain parts of the cerebrum, certain nerves that start in sense 
organs (ear, eye, nose, tongue and skin) have their endings; 
therefore, without the cells of the cerebrum, we would have 
no sensations of hearing, sight, smell, taste or touch, nor 
would we feel hungr}^ tired, cold or warm. In the cerebrum 
are other cells, also grouped in certain parts of the cortex, 
from which fibers run to the voluntary muscles; without these 
cells we could not cause our muscles to obey our will. 

The cerebellum lies behind the medulla and below the dor¬ 
sal part of the cerebrum. The cerebrum is so large in man 
that it covers the cerebellum, which cannot be seen from 
above. (Fig. 213.) A frog whose cerebellum has been re¬ 
moved, cannot sit up; or, if thrown into the water, makes an 
effort to swim, but with irregular and ill-controlled move¬ 
ment. A man whose cerebellum has been injured staggers 
in his walk as though intoxicated. One function of the cere¬ 
bellum, therefore, is to keep the muscles ready for action, 
and to make the muscles used in walking, standing and run¬ 
ning act together in an orderly manner, or, in other words, 
to co-ordinate their action. It probably has other functions 
not yet understood. 

The Medulla.—With both the cerebrum and the cerebellum 
removed, an animal still lives. If this animal is a pigeon, for 
example, placing grains of corn on the ground beside it would 
awaken no response; for without the cerebrum the animal can¬ 
not see nor can it will to act; and without the cerebellum it 
cannot even maintain an upright posture. However, if you 
place a grain of corn in the pigeon’s mouth, the muscles that 
are used in swallowing will act and the grain of corn passes 
down :he throat. The nerve fibers that carry the impulse of 


272 


The Human Body and Its Enemies. 


the grain as it touches the mouth pass to the cells of the me¬ 
dulla, whence fibers pass back to muscles engaged in swallow¬ 
ing. Such action is called reflex action, and will be more thor¬ 
oughly explained below. 

If, now, the animal has lost the entire brain, including the 
medulla, the heart stops 
beating, the breathing move¬ 
ments cease and death oc¬ 
curs. This proves that these 
vital movements are under 
the control of the medulla, 
which is, therefore, some¬ 
times called the “vital 
knot.” Of course, the fibers 
connecting the higher parts 
of the brain with the spinal 
cord and the various parts 
of the body pass through the 
medulla. 

Summary. 

Fig. 215. The brain from below; 1-12 
cranial nerves. 

The brain contains mil¬ 
lions of nerve cells in the cortex, or gray matter, and has 
many fibers running in and out. Many of these fibers are con¬ 
tained in the twelve pairs of cranial nerves that supply the 
head and some of the vital organs. The brain consists of the 
cerebrum, the cerebellum and the medulla. The cerebrum 
performs the higher functions of the mind, as the will, rea¬ 
son, memory, etc. The cerebrum of man is larger than that of 
any of the lower animals. The cerebellum serves chiefly to 
co-ordinate the movements of the muscles. The medulla con- 








The Brain. 


273 


trols the breathing movements, the heart-beat and other vital 
processes. It is the center of reflex action for parts of the 
body and also contains nerve fibers leading from the brain into 
the spinal cord. 

Questions. 


1. How many pairs of nerves run out from the central nervous 
system? 2. What are these together called? 3. Where do the 
branches of the cranial nerves run? 4. What do the flaps at M., Fig. 
217 represent? 5. What are the functions of the cerebrum? 6. 
How would a person with an injured cerebellum act? 7. What is 
the work of the medulla? 8. Why is the tenth cranial nerve, Fig. 
210, the most important one coming off of the medulla? 9. What 
fibers pass through the medulla? 10. What pictures in this chapter 
show parts of the cranial nerves? 


CHAPTER XXXIX. 


The Spinal Cord and Sympathetic System. 

From a study of the functions of the divisions of the brain, 
as described in the preceding chapter, one might conclude 
that they control all of the actions of the organs. They have, 
indeed, a variety of duties. But we shall see in this chapter 
that the spinal cord has independent duties, and that the sym¬ 
pathetic system plays an important part in bringing about 
harmony of action among the organs. 

THE SPINAL CORD. 

Description of the Spinal Cord. —the brain ends and the 
spinal cord begins at the place where the cranial cavity (Fig. 
80a) communicates with the spinal canal. An inspection of 
Fig. 216 discloses the fact that the spinal cord seems to be a 
continuation downward of the medulla. The spinal cord 
differs from the medulla in having the white matter on the 
outside and the gray matter on the inside. (Fig. 212.) The 
cord is about eighteen inches in length and gives off thirty-one 
pairs o.f nerves. Like the brain, it is covered by the meninges 
(M, Fig. 217), and is further protected by a bony covering, 
the vertebrae. The relation of the spinal cord and its nerves 
can best be seen by a study of Fig. 216, and the internal struc¬ 
ture by a study of Fig. 217. The gray matter is seen to be 
shaped in section like the letter H, the four points of the let¬ 
ter representing the four ridges (R) that run up and down 


The Spinal Cord and Sympathetic System. 


275 


.X 






the spinal cord. There are, therefore, on each side two ridges, 
a dorsal and a ventral, and from each comes off a bundle of 
nerve fibers called a root. So on each 
side there is a dorsal root (DR) and a 
ventral root (VR), which unite outside 
the spinal cord into a nerve, the spinal 
nerve (N). The dorsal root has a gang¬ 
lion—the dorsal ganglion (DG). The 
function of these parts has been deter¬ 
mined by experiment as outlined below. 

Functions of the Spinal Cord. —It was 
noted above that the spinal cord carried 
some of the fibers down from the medulla. 

It thus acts as the pathway from distant 
parts of the body to the brain and back 
from the brain to the parts of the body. 

That it has other functions can be shown 
by experiment in the same way as the 
functions of the parts of the brain have 
been discovered by experiment. 

If we take a frog that has been freshly 
killed by the removal of the whole brain, 
we find that the spinal cord can act like 
the medulla in completing certain nerve 
circuits. If we irritate the chest of the 
brainless frog, the front legs move to 
scratch at the irritated parts; or if the 
skin of the toe is irritated, the foot is 
Jerked away. This shows that nerve im¬ 
pulses pass into the spinal cord from the Fl ^ e 2 S pi na i T cord b with 
outside (from the chest or the foot, for °sympa? 

example), and that impulses pass out of et the n right S siS 1 . ia 









276 


The Human Body and Its Enemies. 


again to the muscles to remove the irritated part. When the 
spinal cord is also removed, no muscular response to irritation 
occurs. This proves that the spinal cord has the important 

function of sending the 
proper message back down 
the outgoing nerve when¬ 
ever an incoming message is 
received. In other words, 
the spinal cord is the center 
of reflex action. 

Two Kinds of Nerve Fi¬ 
bers. —When you will to 
move your index finger, you 
send an impulse to the mus¬ 
cles that move it, and the fin¬ 
ger moves. When you touch 
an object with the finger, you 
feel the object,; this time a 
different impulse pas s e s 
along the nerve. One kind 
of impulse goes out from the 
center to a muscle and re¬ 
sults in motion. It is called 
a motor impulse, and uses 
its own nerve cells and their fibers, which are called, there¬ 
fore, motor cells and motor fibers. The other kind of impulse 
comes in from the outside to the center, and causes us to feel 
(if carried as far as the brain), and is called a sensory im¬ 
pulse. It commences in a sensory cell, runs along sensory fibers 
and ends in relay cells located in the spinal cord, which send 
it on to the brain. Most nerves carry motor and sensory fibers 
bundled up together. In reflex action a sensory impulse en- 



Fig. 217. Spinal cord; cut end with 
portion of white matter (W) cut 
away, exposing: the dorsal ridges 
(R). D, dorsal; V, ventral; WL, 
nerve fibers of white matter cut 
lengrthwise; G, cross-section of gray 
matter; M, meninges or covering 1 
membranes; N, spinal nerve; DR, 
VR, dorsal and ventral roots; DG, 
dorsal or sensory ganglion. 

















The Spinal Cord and Sympathetic System. 


277 


ters the spinal cord and is returned by cells of the cord as a 
motor impulse running along motor fibers to the proper mus¬ 
cles. 

Reflex Action. —The path of nerve impulses in reflex ac¬ 
tion can be demonstrated by the experiment illustrated in 
Fig. 218. (Compare with Fig. 217.) Suppose the spinal nerve 
(N) supplies the arm and fingers. Experiments in cutting the 



Fig:. 218.—Illustrating method of experiment on motor and sensory fibers. 
A, spinal nerve cut through; B, dorsal or sensory root cut through; 
C, ventral or motor root cut through. Other letters as in Fig 217. Num¬ 
bers indicate points where nerve fibers are stimulated in experiment. 


nerve and its roots (VR and DR) would result as follows: 

If the nerve N be cut at A 

Irritation at 1 would cause pain. 

Irritation at 2 would make the finger move. 

If the dorsal root (DR) be cut at B 
Irritation at 3 would cause pain. 

Irritation at 4 would have no effect. 

If the ventral root (VR) be cut at C 

Irritation at 5 would have no effect. 

Irritation at 6 would make the finger move. 

What do you learn from this? Sensory nerve fibers pass 
into the spinal cord by the dorsal root (note the arrow) and 
motor nerve fibers pass out by the ventral root. The spinal 
nerve (N) contains what kinds of fibers? Any impulse from 
the fingers or hand (say, touching a sharp point), then, passes 
up the spinal nerve (N, Figs, 217-219) through the dorsal root 


278 The Human Body and Its Enemies. 

and the cells in the dorsal ganglion to sensory nerves in the 
dorsal ridge of the spinal cord; here the impulse is passed on 
to cells in the ventral ridge of the gray matter, which starts a 
motor impulse that passes out at the ventral or motor root 
along the spinal nerve to the muscles of the arm. (See Fig. 
219.) This is the machinery of reflex action. This works so 
perfectly that the impulses are always sent back to those 
muscles best calculated to afford relief. The spinal cord is 
the reflex center for a large part of the body—the central 
station to which sensory impulses come, and where these are 
passed on to motor cells, causing motion in the. proper 
muscles. 



Fig:. 219. Diagram illustrating: path of nerve impulses in reflex action. 


You have noticed that when you touch the point of a tack 
unawares, your finger is withdrawn before you think. The 
sensory impulse in the spinal cord is also passed on to fibers 
leading to the cerebrum, causing there conscious sensation— 
that is, we feel. After thinking it over, we would will to 
remove the finger. But this far-around way takes so long that 
much harm would be done the finger by the tack before we 
could think it over. The circuit through the spinal cord, the 
path of reflex action, is rapid and its purpose is largely to 
protect the body against sudden dangers. 



The Spinal Cord and Sympathetic System. 


279 


Observation Work.—Give six other examples of how reflex action 
is of service to you. 


THE SYMPATHETIC SYSTEM. 


We have thus far studied only the central nervous system 
and the cranial and the spinal nerves. 

Closely connected with these by fibers 
is the sympathetic nervous system, or 
ganglionic system, as it is also called, 
because its cells are grouped in numer¬ 
ous ganglia. The ganglia are located in 
two chains, one on each side of the spi¬ 
nal cord close to the backbone (the left 
one shown in Fig. 220, the right one 
Fig. 216) ; and there are in addition to 
the chains several ganglia and bunches 
of nerve fibers, called plexuses, about 
the organs of the chest and abdomen, 
especially behind the heart and the 
stomach. A blow over the stomach, 
where the “solar plexus’’ is located, 
paralyzes the ganglia there, and may 
cause sudden death. 

Function of Sympathetic Nerves.— 

Can you make your heart beat faster 
or slower at will, as you move your fin¬ 
ger at will? When you walk or run it 
beats faster whether you will or not. 

After you exercise considerably your 

skin becomes red and the sweat glands Fig:. 220 . The sympathetic 

0 g:ang:lia and nerves of 

act. All these functions are regulated body left side ° f the 




280 


The Human Body and Its Enemies. 


largely through the sympathetic nervous system. When you 
chew food, digestive glands secrete their juices. The organs of 
secretion, the heart, the kidneys, the muscles of the arteries 
and the digestive organs are controlled in part by the sympa¬ 
thetic nervous system, and in part by the nerves coming from 
the medulla. These involuntary acts are called automatic. 
That the cerebrum also has something to do with automatic 
acts (secretion of saliva, for example,) can easily be seen from 
the fact that if you watch a person sucking a lemon and mak¬ 
ing a wry face, or even if you think of this sight (a cerebral 
act), your mouth will ‘‘water.” An impulse thus passes along 
the nerve of sight to the sensory cells of the cerebrum; thence 
by fibers (Fig. 214) to other brain cells whose fibers run out 
to the salivary glands. Sympathetic nerves also go to the 
salivary glands. 

Advantages of Automatic and Reflex Action. —In the first 
place, since the cerebrum is the organ of thought, will, mem¬ 
ory and other powers, it is important that we relieve the cere¬ 
brum from many of the petty acts of life, so as to leave it free 
to perform more of the higher functions. Thus, the sympa¬ 
thetic system and the medulla keep us breathing and regulate 
the heart-beat, make the digestive glands secrete at the proper 
time—in short, the lower centers attend to all of the automatic 
acts necessary for life. We could not regulate all of these 
things if we would. In the beasts of the field automatic action 
is as perfect as in man. 

The reflex centers also relieve the cerebrum. Reflex acts 
are not only protective, being more rapid than voluntary acts 
(page 278), but they save us from giving voluntary attention 
to them. Take walking, for example; a child learning to 
walk must give his whole attention to the act. If you had 
to do so you could not find time for much else. So it is with 


The Spinal Cord and Sympathetic System. 


281 


eating, washing, dressing, tying a knot, or performing a thou¬ 
sand other things that we do without thinking. Tying our 
necktie is at first a conscious act, and requires the work of 
the cerebrum; but later, after practice, the cerebellum takes 
charge, and we tie the necktie while thinking of something 
else. 

Experiment.—Write the word “Practice” on a white sheet of pa¬ 
per. You write it easily and without thinking how each letter was 
made or how the word was spelled. Now copy the characters in 
Fig. 221 immediately below the word 
just written, and after doing so, turn 
the sheet around and hold it up to the 
light. Why did you write the first more 
easily than the second? A child who 
has never written a word would find it 
harder to write the word “Practice” 
than you find it to write the characters 
in Fig. 221, which is a mirror image of the word “Practice.” 

It is important in early life to reduce as many conscious 
acts as possible to reflex acts. When the multiplication table 
is once learned, that much of life’s work is laid aside. One 
should learn to read, to write, to spell, to draw, to work arith¬ 
metic, and to do as many other things as possible early in life 
so that later these can be performed by the lower centers, 
leaving the cerebrum free for higher thought. Education 
should, therefore, begin early, and every day possible should 
be spent at school. 

Habits. —When an act is done once it is easier to repeat it, 
and the oftener it is repeated the easier it is done and the 
more one tends to do the act. It soon becomes a habit. Habits 
are hard to break, for it is difficult for the nerves to act differ¬ 
ently from the way they have often acted. Bad habits can 
be broken, however. The way to “break a habit is to break 
it.” It is difficult, the first time we try; to keep from doing 




& 


282 


The Human Body and Its Enemies. 


a bad act that has become habitual; but the second time it 
is easier, and so on until it becomes a habit to abstain from 
the act. It is best to acquire good habits and never form bad 
ones. Habits are mostly formed in youth. This fact makes 
education in the home and in the school important because 
education makes a girl or a boy acquire correct habits of 
thinking and acting. A person with many good habits will 
be more successful in life than one with bad habits or too few 
useful ones. 

Summary. 

The spinal cord has two main functions. First, it carries 
sensory impulses from the outside to the brain and motor im¬ 
pulses from the brain to the outside. It is, therefore, a cable 
of fibers and relay stations. The fibers are located in the white 
matter of the cord and in thirty-one pairs of spinal nerves and 
their roots; the nerve cells are found in the gray matter of the 
cord and in the dorsal ganglia of the spinal nerves. 

The spinal cord, furthermore, acts as a reflex center; that 
is, it is able to receive sensory impulses and translate them 
into motor impulses. This may be called the 1 ‘short circuit” 
of reflex action, as distinguished from the “long circuit” 
through the cord and the brain, which results in conscious 
action. 

The sympathetic nervous system has as its centers certain 
ganglia in the dorsal wall of the chest and abdomen. It sends 
out fibers through the body, especially to the vital organs, 
and helps to connect all the parts and bring about complete 
harmony of action among the heart, lungs, digestive organs, 
glands and other organs of the body. The sympathetic nerves 
are not under the control of the will but act entirely auto¬ 
matically. 


The Spinal Cord and Sympathetic System. 


283 


Automatic and reflex acts are important, first, to regulate 
the work of the vital organs, and, second, to relieve the cere¬ 
bral cells of acts that have become habitual by practice. The 
right kind of education early in life is, therefore, very im¬ 
portant in order that correct habits of work, thought and 
conduct may be formed. 


Questions. 

1. Where in the body are the organs pictured in Fig. 216 lo¬ 
cated? 2. With Fig. 217 before you, describe the structure of the spi¬ 
nal cord. 3. In what direction do impulses pass along motor fibers? 
4. Along sensory fibers? 5. Draw Fig. 218 on the board and explain 
the course of sensory and motor impulses into and out of the spinal 
cord. 6. Explain exactly how it is that a frog with its head cut off 
can draw up its leg if its foot is irritated. 7. What is meant by 
reflex action? 8. Give examples of action of the sympathetic nerves. 
9. Why must the vital processes be automatic? 10. State the ad¬ 
vantage of reflex action. 11. Why is it best to get as much school 
education as possible while young? 12. How are habits formed? 
13. How may bad ones be broken? 


CHAPTER XL. 


The Care of the Nervous System. 

The nervous system is both the most wonderful and the 
most delicate part of the human body. It is also more closely 
connected with our real or spiritual selves than any other part. 
The nervous system not only co-ordinates all our organs, as 
has been pointed out in Chapter XXXVIII, but also regulates 
our relations with the world around us. The care of the ner¬ 
vous system, therefore, becomes* the most important problem 
of hygiene. The man who solves the problem of how to keep 
an active, efficient nervous system has largely solved the prob¬ 
lem of correct living. 

This is also a difficult problem, and you cannot expect to 
learn all about it in a single year. In fact, you must learn 
a great deal from experience. In this book, we can only hint 
at some of the important points to bear in mind with refer¬ 
ence to the nervous system. These points we may summarize 
in the following rules: (1) Keep the body in general good 
health according to the rules of hygiene thus far learned; (2) 
avoid all stimulants except when they are prescribed by a 
physician in case of sickness; (3) form good habits; (4) avoid 
the poisoning which results from germ diseases like typhoid 
fever, scarlet fever, grip, and others; (5) keep the stomach in 
good order; (6) avoid worry^, overwork and mental strain; 
(7) sleep sufficiently; (8) take enough recreation. 

Habits. —We shall take up first the subject of habits, as 
stimulants are treated in the next chapter. Habits are men- 


The Care of the Nervous System. 


285 


tal and moral as well as physical. Among bad habits may 
be mentioned that of spitting on the floor, which is, of ocurse, 
a physical habit. A bad mental habit is that of giving poor 
attention to one’s studies. Giving way to fits of anger is a 
bad habit, both from a moral and a physical standpoint. The 
sum total of a man’s habits forms his character. Most people 
have more good habits than bad ones, and would have fewer 
bad habits if they realized how easy it is to prevent a habit 
if one begins in time. 


The nervous system is damaged severely by germ diseases. 

We often see young people so weak¬ 
ened by a spell of typhoid fever, for f 
instance, that it is years before they,* 
can perform with comfort their or¬ 
dinary duties. All the germ diseases 5 
set free poisons in our blood. These 
poisons injure the delicate ner 



cells. While it is not an everyday oc¬ 
currence to see insanity as a result 
of the severe infections like small¬ 
pox or typhoid fever, such things do 


Figr. 222. All the catching- 
diseases leave the nerv¬ 
ous system weakened to 
to a greater or less de¬ 
gree. 


occur. If you have ever had the grip, you know how weak, de¬ 
pressed and miserable even a mild germ disease can make you 
feel. You can imagine, then, the terrible harm that can result to 


the nervous system when a patient lies for weeks in a delirium 
due to the poisons of typhoid fever. From a standpoint of 
prevention, therefore, many nervous diseases are germ dis¬ 
eases. That is, they are caused by germ diseases, and if we 
prevent the germ diseases, we prevent the nervous diseases 


which follow. 


A deranged stomach also is very important as a cause of 
nervous disease. The stomach is very richly supplied with 








286 


The Human Body and Its Enemies. 


nerves, both from the brain and from the sympathetic system. 
The solar plexus (Fig. 220) supplies many nerves to the stom¬ 
ach. The close connection between the stomach and the 
nervous system is shown by the fact that fright can make 
some people sick at the stomach, or nauseated. Strong ex¬ 
citement or anger interferes with appetite and digestion. For 
this reason, it is very important that only pleasant topics 
should be discussed at meal time. Also, if we are careless in 
our eating habits, and swallow the food hurriedly, or eat at ir¬ 
regular hours, or fail to masticate our food properly, it is 
very likely to upset the stomach and make us very nervous 
and miserable. There is one kind of dyspepsia that is called 
nervous dyspepsia; few people are so completely miserable as 
these nervous dyspeptics. 

Overwork.—A reasonable amount of work helps to keep 
the body in good condition and 
makes one enjoy his leisure and his 
sleep. But this work must be regu¬ 
lated according to the strength of the 
worker. One man can stand twice 
as much work as some other man. It 
is said that Mr. Edison, the inventor, 
can work eighteen hours a day for 
days at a time; but it is likely that 
this would wear out the average man 
in a week’s time. Some people of 
delicate constitution can work only 
an hour or two at a time without 
being fatigued. When one works too long or too hard, he 
notices that he cannot do quite as good work as usual, and 
that he does not enjoy his work as much. If he keeps on 
trying to drive himself to work as hard as ever, he finds that 



Fig. 223. This represents a 
man who has been very 
much overworked. 



The Care of the Nervous System. 


287 


he is depressed and becomes discouraged easily. He gets the 
“blues,” and becomes more irritable than is his habit. He 
is likely to become nervous and sleepless, and may lose weight. 
He feels tired even on rising in the morning, and spends a 
very miserable existence indeed. 

It is often difficult to say whether a boy is overworked or 
whether he is merely lazy. One indication of laziness in work 
is that the individual is interested in something outside of 
his work, a thing not likely to be the case with an overworked 
boy. 

We should remember, however, that people of an enthusi¬ 
astic, eager disposition are more likely to overwork them¬ 
selves than those of a reserved, smooth temperament. If 
you are of an enthusiastic disposition, there may be times 
when you feel overworked, and in these times you should 
talk with some older relative, such as a father, sister or 
guardian. Oftentimes an outsider can plainly see what we 
ourselves overlook. 

A nervous breakdown resulting from overwork, is a se¬ 
rious matter in the case of people of moderate means. The 

cure for it is a change of scene and habits, which is expen¬ 
sive. Hence it is wise to avoid a breakdown. Longer 
hours for sleep and recreation, and more cautious use of 
exercise should be begun as soon as signs of a nervous break¬ 
down occur. 

Sleep. —One who sleeps enough is not likely to suffer a 
nervous breakdown. Sleep is the cure for worry and over¬ 
work. A child of twelve should sleep nine to eleven hours 
a day. A man doing hard physical labor should sleep at 
least eight hours a day. Intellectual laborers should sleep 
an hour more. Those who have a delicate constitution should 
take a nap in the middle of the day, especially in warm weather. 


288 


The Human Body and Its Enemies. 


Recreation is next to sleep in importance. Every man needs 
some exercise which he can take with so much pleasure that 
he forgets himself. That is the true test of recreation: if it 
causes the player to forget himself in the enjoyment, it is true 
recreation. Men* who perform hard physical labor usually 
like some recreation which employs the mind more than the 
body, such as music or reading. Intellectual workers usually 
prefer some form of recreation which calls the muscles into 
play, like tennis or hunting. Any exercise that is done for 
the sole purpose of building up the 
body, especially if it is unpleasant, 
is not true recreation. To get the 
most good out of recreation, it must 
be enjoyable. In Texas, the climate 
is such that outdoor exercise can be 
enjoyed all the year around, and 
all persons who have a nervous 
tendency should try to spend a 
large part of the time out of 
doors, provided they can find some 
congenial occupation or recrea¬ 
tion. 

The Nerve Cells. —The nerve cells are the seat of those ner¬ 
vous changes which go to make up our conscious life. When 
the nerve cells are well nourished and fresh, we feel well; 
when the nerve cells are tired, exhausted, or starved, we feel 
bad. The nerve cells are so delicate that we cannot handle them 
after death without destroying them, and so, up to this time, 
we have never seen many of the changes which occur in nerve 
cells as a result of fatigue or of poisoning. This is best seen 
in the cells of animals which are hard at work all day, such 
as the bee or the swallow. If the central nerve cells of these 



Fig. 224. Sleep is the great¬ 
est restorer of wornout 
nervous systems. 




The Care of the Nervous System. 


289 


little beings are examined at night, they appear shrunken and 
irregular in outline. In the morning, while the little creature 
is fresh and strong, the nerve cells seem to be well rounded 
out. This is shown in Fig. 225. We know, then, that we 
cannot do good work with wornout nerve cells or with pois¬ 
oned nerve cells. Disease germs, alcohol or morphine cause 


poisoning of the nerve cells. 
Rest, recreation and sleep re¬ 
store the cells to their proper 
strength and vigor. 

Just as the mind is the 
highest function of the 
nervous system, so the judg¬ 
ment is the highest faculty 
of the mind. Nowhere in life 
de we need good minds and 
good judgment more than in 
the regulation of our lives so 
as to keep our nervous sys¬ 
tems in good order. 



Fig-. 225. The picture to the left is 
a fresh, unfatigued, nerve-cell. The 
middle picture is a moderately fa¬ 
tigued nerve-cell. The picture to the 
right is a nerve-cell poisoned by 
alcohol or disease. 


Important Points. 

The enemies of a good nervous system are as follows: 

1. General poor health from other causes. 

2. Stimulants, such as alcohol, tea and coffee. 

3. Bad habits, and excesses of all kinds. 

4. Germ diseases like typhoid fever. 

5. Improper habits of eating, causing imperfect digestion. 

6. Worry, overwork and mental strain. 

7. Lack of sleep and recreation. 



290 


The Human Body and Its Enemies. 


Questions. 


1. Name some stimulants which may cause nervous disease. 2. 
Name all the germ diseases which you know. 3. Name some bad 
habits. 4. Explain why the stomach is concerned in nervous dis¬ 
orders. 5. Explain the importance of sleep. 6. Explain what is 

meant by recreation. 7. If a man practices with dumb-bells in 
order to gain muscle, is this recreation? 8. How, then, can you tell 
whether an exercise is true recreation or not? 9. What is the dif¬ 
ference between the nerve cells of a bee early in the morning and 

at the close of a busy day? 10. What kind of persons are likely 
to be overworked? 


CHAPTER XLI. 


Alcohol, Narcotics and Stimulants . 

In the pages that have gone before you have learned how 
the liquid poison called alcohol can injure the various organs 
of the body, but this poison acts in such a stealthy and pecu¬ 
liar way that we shall devote some time now to the study of 
the poison itself, how it affects the human body, and how to 
avoid it. 

Alcohol. —Pure alcohol is a clear, colorless liquid, somewhat 
lighter than water. It mixes with water very readily, and 
in so doing produces some heat. Alcohol evaporates rapidly, 
and for this reason, when placed on the skin, feels cool as it 
evaporates into the air. If it be placed on the skin and then 
covered, however, it feels hot and causes reddening of the skin. 
It is made from fermenting sugars. In the process of making 
alcohol, the yeast germs change the sugar to alcohol, and in 
so doing they cause carbonic dioxide to bubble out of the fluid. 
If the yeast germs are allowed to remain in the water and 
sugar solution, there comes a time when they have formed so 
much alcohol that they can no longer live in the mixture, and 
they die. Other germs are less able to live in the alcohol so¬ 
lution than the yeast germs. 

From this it might be supposed that alcohol is good for us, 
because it kills germs. But in the chapter on disinfectants 
we have already learned that if we desire to kill germs in the 
human body we must use something more poisonous for the 
germs than for our bodies. Alcohol is just as poisonous for 


292 


The Human Body and Its Enemies. 


us as it is for the germs, and in fact, it gives the germs the 
advantage by upsetting our system. So it is not a useful 
drug for killing germs in the human body. 

Percentage of Alcohol in Whiskey, Beer and Wine. —We 
have learned that pure alcohol is a clear liquid; but the drinks 
sold to the public do not usually contain more than fifty per¬ 
cent of pure alcohol. Whiskey and brandy contain about 



Fig. 226.—Althougrh beer and wine contain a lower percentage of alcohol 
than whisky, a drink of beer contains about the same amount of ac¬ 
tual alcohol as a drink of whisky. The tall graduated glasses represent 
the amount of absolute alcohol in a single drink of beer, whisky, and 
wine. 


fifty percent alcohol. The wines contain from seven to twenty 
percent and beer contains from one to five percent of alcohol. 
Practically all that any of these liquors contains in addition 
to the alcohol is some sugar, flavoring and coloring matter. 
The picture shows that the amount of pure alcohol contained 
in an ordinary drink of whiskey is about the same as that con¬ 
tained in a drink of beer or wine. 

It is most remarkable how this alcohol attacks each and 
every organ of the body with which it comes in contact. 

The stomach is affected very badly by alcohol, and it be¬ 
comes inflamed from the irritating action of liquors contain¬ 
ing this substance. Indigestion, loss of weight, and a general 












Alcohol, Narcotics and Stimulants. 


293 


condition of invalidism are signs of the bad effects which the 
alcohol has on this particular organ. The liver feels the 
presence of alcohol also, and shows it by becoming tough and 
fibrous from the scar tissue or connective tissue, which is 
caused by alcohol. When this has once developed there is 
no hope for the patient ever to recover, and as a rule the 
drinker does not know he is threatened with this trouble until 
it is too late. 

The respiratory system is affected somewhat by alcohol. The 
fumes or odor of alcohol can be detected in the breath, which 
means that the lungs are doing their part to throw the poison 
out of the system. The main point, however, is that alcohol 
makes people so much more susceptible to the inflammations 
of the lung, such as pneumonia. Persons that drink alcohol 
are more likely to die when they have pneumonia than others. 
Physicians always inquire if a patient has used alcohol when¬ 
ever they are called in to treat a case of pneumonia. This 
disease is dangerous at any time, but especially so when it oc¬ 
curs in drinkers. 

The kidneys help the lungs rid the system of alcohol, and in 
throwing this poison off the kidneys are somewhat injured. 
Their injury is one that can never be repaired, and when a 
drinker has caused nephritis or kidney disease by his bad 
habits, it is too late to remedy the matter. Nephritis means 
an injury of the little kidney cells (XYZ, Fig. 174). Like 
the liver cells, the kidney cells are replaced to some extent by 
connective tissue when they are inflamed. 

The heart is injured by drinking alcoholic liquors because 
the liquid has to be pumped to the lungs and to the kidneys 
to be thrown off from the body. The heart is made to pump 
more blood than the needs of the body demand; and it 
seems reasonable to suppose that a heart is overloaded when 


294 


The Human Body and Its Enemies. 


one drinks much liquor. The alcohol in the blood also hard¬ 
ens the arteries and causes the growth of scar tissue, which 
can be seen in spots in the arteries after death. 

The muscles and bones are injured by alcohol, because they 
suffer from want of good food. If the stomach is inflamed, 
it cannot prepare food for the body’s needs, and for this rea¬ 
son persons who drink large amounts of alcohol are usually 
weak and feeble. 

The nervous system is so delicate and so wonderful that it 
must be taken care of properly or it will certainly get out of 
order. The most wonderful watch that was ever made, when 
compared with the human nervous system, is as clumsy and 
awkward as an ox wagon. The delicate machinery of brain, 
spinal cord and nerves has to do with the proper control of 
our organs and also with our thoughts. Think what dreadful 
consequences must follow the injury to these little cells which 
form our thoughts. Alcohol does injure them, for alcohol is 
the cause of more cases of insanity than any other cause ex¬ 
cept heredity. Probably about twenty percent of all insanity 
is due entirely to alcohol. 

How the Drink Habit Is Formed. —It is not stated anywhere 
in this book that all persons who use alcohol will develop any 
of the diseases mentioned. In fact, there are some people who 
do not seem to be injured by alcohol, so far as we can tell. 
Such persons are to be compared with typhoid carriers. You 
remember that some persons have the typhoid germs in their 
bodies without showing any symptoms. These persons are 
well and strong, and so far as they are concerned are none the 
worse off for having the germs; but they spread the disease 
to others. So it is with drinkers: some of them take the al¬ 
cohol into their systems without showing any immediate ill 
effects on themselves, but they spread the drink habit. Other 


Alcohol, Narcotics and Stimulants. 295 

young men and boys see them drink, and follow their example. 
In the case of germ diseases, a person who has a mild case 
may give the disease in its worse form to another person; so, 
a man who drinks just a little can give the germ of the habit 
to another man, who may drink himself into his grave or into 
the asylum. 

Probably all of you know how low alcohol can drag its victim. 
You have no doubt heard of or possibly seen a drunkard, with 
his staggering gait, his unkempt hair, and his bleary eyes. 
Such a poor drunkard goes about exposing himself to the 
weather, and leaves his family to look out for themselves. He 
is not himself, and that marvelously beautiful instrument, the 
brain, is in such poor working order that he is little better 
than an idiot. A drunkard may scowl at his best friend, as 
though he hated him, or may speak roughly to a little child; 
on the other hand, he may look on a scene of sadness and 
chuckle as if it were a joke. 

You may be sure that no man ever expected to be anything 
like this when he took his first drink. And yet it is impos¬ 
sible to tell beforehand just who will develop into a drunkard. 

Since, then, alcoholic drinks are absolutely worthless to the 
user, and may cause irreparable harm to body and mind, it is 
best never to begin to drink. When invited by a friend to 
drink with him it takes “grit” and force of character to re¬ 
fuse to be led into so dangerous a habit. Make up your mind 
that, when you are in the situation of the young man shown 
in Fig. 227, you will decline. 

It is wise for business reasons to leave alcohol absolutely 
alone, for many business firms will not employ anyone who 
drinks. This is true especially of banks, railways and other 
business firms who are entrusted with people’s property 
or people’s lives. Athletes, who are ambitious to ex- 


296 


The Human Body and Its Enemies. 


cel, always leave alcohol alone when preparing for a con¬ 
test. Locomotive engineers must not drink, for the lives of 
the passengers are in their hands. Lawyers must work hard 
at times, and sometimes an innocent man’s life depends on 
the good work of the lawyer defending him; in a case of this 

kind alcohol is a hin¬ 
drance* The physician 
fighting disease cannot af¬ 
ford to drink, as it would 
make him unfit to give ad¬ 
vice to the patient de¬ 
pending on him. In fact, 
it might be said that any 
good work demands of a 
man that he leave alcohol 
alone. Drinking is out of 
place in the life of any 
ambitious man. It is a job 
to itself, and should be 
left to those who have no 
ambition or desire to take 

Tea and Coffee. —Somewhat akin to the alcohol question, 
but of less importance, is the tea and coffee problem. Both 
tea and coffee contains a substance which in its pure form 
exists as white crystals, called theine or caffeine. This sub¬ 
stance acts as a powerful stimulant to the muscles, the nerves 
and the mind. After the first effect passes off, the drug 
causes a certain amount of depression and discomfort. In 
mild doses it is not very harmful to some people, but it is al¬ 
ways risky to tamper with stimulants. In the long run, any 
man can do more work without stimulants than with them. 



Fig. 227. The first drink is almost al¬ 
ways taken to accommodate a friend. 
Have your mind made up beforehand 
never to take the first drink. 


part in the work of the world. 







Alcohol, Narcotics and Stimulants. 


297 


It is rather cowardly to take stimulants in order to stand up 
under a special strain. A man should face his trials man¬ 
fully, whether they are an extra hard day’s work, a tedious 
examination, or some other hardship. It undermines a man’s 
self-reliance to use stimulants to give him temporary strength 
to perform his duty. 

Opiates. —Caffeine is one of the strongest stimulants we 
have, and it does increase capacity for work temporarily. It 
stimulates the intellectual faculties or thinking powers of the 
brain. There is another drug which stimulates another part 
of the brain, and this drug is opium or morphine. Opium is 
the dried juice of the poppy, and morphine is a white crystal¬ 
line substance which represents the strength of opium. Opium 
and morphine do not increase the intellectual powers, but they 
stimulate the imagination and relieve pain. These drugs are 
even more deadly than alcohol, because they are likely to 
eause the opium or morphine habit. You can have no idea 
how these drugs cause one to long for them after having taken 
them a few times. When the effect wears off and the dread¬ 
ful after-effect comes on, the poor morphine habitue is ner¬ 
vous and miserable, and frequently ends his life. It is very 
hard to shake off the morphine habit. It is against the law 
for these things to be sold in Texas except on a physician’s 
prescription, and all conscientious physicians take precautions 
in the use of these deadly drugs, in order to prevent their 
patients from forming the habit. Laudanum, paregoric, Do¬ 
ver’s powder, cocaine, some headache powders or capsules, 
belong to the same class of remedies. It would be well for 
you to make it a rule never to take any medicine to relieve 
pain except on the advice of a competent physician or dentist. 


298 


The Human Body and Its Enemies. 


Important Points. 

1. There was never a drunkard yet who believed at the 
time he took his first drink that he would become a drunkard. 

2. Alcohol injures all the organs of the human body, but 
does its greatest harm to character. 

3. The first drink is usually taken to accommodate a friend. 

4. Tea and coffee act as stimulants, but in the long run 
do not increase one’s ability to perform work. 

5. Morphine, opium, soothing syrups, headache powders 
and capsules, should only be taken under the advice of a com¬ 
petent physician. 


Questions. 

1. How is alcohol made? 2. Alcohol does not help the body 
destroy germs, although alcohol itself will kill germs. Why is this? 
3. In what way does alcohol do its greatest harm to the body? 4. 
Since beer contains a smaller percentage of alcohol than whiskey, 
explain why it is that a drink of beer contains as much alcohol as 
a drink of whiskey. 5. Why 'is it dangerous to take medicines to 
relieve pain without consulting a physician? 


CHAPTER XLII. 


The Special Senses. 

General Sensations. —It was noted above that there are two 
kinds of nerve fibers, sensory fibers carrying impulses into the 
central nervous system, and motor fibers, carrying impulses 
out to the muscles. In reflex action sensory impulses may 
pass only to the spinal cord and be there changed to motor 
impulses that pass out to the muscles. If the sensory impulses 
reach the cerebrum they result in sensations. When meal-time 
arrives w r e feel hungry; if water is needed, we are thirsty. 
Hunger and thirst are due to impulses that arise from all parts 
of the body. They are, therefore, called general sensations. 
A feeling of fatigue and of nausea are other general sensations. 
They are useful in serving as a guide to the general condition 
of the body. 

The Special Senses. —The special senses (touch, taste, smell, 
sight, hearing,) differ from the general sensations in that each 
has a special organ that has to do with a particular kind of 
sensation. Thus the skin is the organ of touch, the tongue of 
taste, the nose of smell, the eyes of sight and the ears of hear¬ 
ing. These organs are called the organs of the special senses, 
by which we feel, taste, smell, see and hear. The special senses 
are the five gateways of the mind, for through them we learn 
all we know about the things around us. Since this is true, it 
is very important that we train the senses so that they may, 
through practice and habit, become our skillful servants. 

Four Conditions Needed for Sensations. —In studying the 


300 


The Human Body and Its Enemies. 


special senses we must remember that, to have any sensation, 
a number of things are necessary. (1) There must be a proper 
stimulus, for without something touching the skin we could 
not feel, or without light we could not see. (2) There must 
be cells (the ‘‘end cells”) in the sense organ to catch up these 
stimuli, magnify them and translate them into nerve language 
and pass them on. (3) From the end cells sensory nerve fibers 
must take the nerve impulse to the brain; if the nerve of sight 

were cut, for instance, we 
should be blind. (4) The cortex 
of the cerebrum must be active, 
so as to receive the impulse and 
produce the sensation. If any 
one of these four is absent or 
injured, there can be no sensa¬ 
tion. In studying the sense or¬ 
gans we shall make it a point 
to study the location of the end 
cells and to discover how the 
various stimuli reach these cells. 

Touch. —The skin is the or¬ 
gan of touch. As shown in Fig. 
176, and again in B, Fig. 228, 
there are, in the dermis nearest the epidermis, groups of cells 
called “touch buds,” among the cells of which the sensory 
nerve fibers end. When an object touches the skin, it 
presses against the touch buds and stimulates the nerve 
fibers; the impulses are then carried to the brain and we have 
the sensation of touch. If the pressure is even over the skin we 
feel the object as smooth; if the pressure is greater in spots, we 
feel the object as rough. Hard, soft, sharp, dull, etc., describe 
how objects feel from the way they press against the skin. 



MfcRVfc 


Fig-. 228. Papillae of the skin; A, 
epidermis; 1 and 3, papillae with 
blood vessels; 2 , papilla with 

touch bud. 








The Special Senses. 


301 


Experiments on the Sense of Touch.— (1) Some parts of the skin 
are more sensitive to pressure than others, as can be observed read¬ 
ily by experiment. Take a bristle from a whisk-broom or clothes- 
brush and press it against the skin of the nose, forehead, lips, back 
of neck, tips of fingers, etc. (2) Another test for sensitiveness of 
touch can be made by finding out for any region of the skin the 
greatest distance apart two points pressing on the skin will be felt 
as one point. Take a blunt pair of scissors and place the two points, 
separated one-sixteenth of an inch, on the tips of the fingers of a 
person, who should have his eye shut or be looking away. Are 
they felt as one point or two? Repeat the experiment for different 
regions of the skin, separating the points more or less. At the tip 
of the tongue two points can be distinguished as two when only one- 
sixteenth of an inch apart, or less; on the back of the neck the 
points may be several inches apart and still felt as one point. Try 
this on different persons, but try to confuse the person experimented 
upon by alternating the application of a single point and of two 
points. 


The Temperature Sense. —At some places in the skin certain 
nerve fibers end in cells not a part of touch buds. These are 
fibers that carry sense impulses of heat and cold. 


% 

6 • 
• 

o 


’ * *0 

• « 

0 o 

o * 


Experiments.—Mark out a spot 
one by two inches on the inner 
surface of the forearm. With a 
small blunt-pointed piece of metal 
(as a nail) colder than the body, 
find the cold spots by moving the 
metal slowly over the surface. 

Mark the cold spots with red ink. 

With a warm piece of metal find 
the warm spots in the same way, 
marking with black ink. (See Fig. 229.) 
day. 


• o 


% 

• o 


" ♦ % 
O t O * 


*0 V 

o o * 


0 4 °Q * 
• « 0 


0 % Q 


, o * 0 • 


0. • 


m = WARM SPOT o = COLD SPOT 

Fig:. 229.—“warm” and “cold” spots 
from a portion of the skin of 
the wrist; natural size. 


Try it again the next 
Do the nerves at these spots act the same each day? Do you 
think there are special nerve fibers that carry special messages to 


the brain? 

As there are likewise spots in the skin that cause pain when stim¬ 
ulated, these also may be located. Pain is in part a general sense, 




302 The Human Body and Its Enemies. 

and nerves carrying impulses to the brain cause pain when strongly 
stimulated. Pain is useful in that it gives warning of danger and 
teaches us what is harmful to the body, so that conditions causing 
pain my be avoided. 

Taste. —If we say the skin is the organ of touch, then the 
tongue is the organ of taste. Just as there are touch buds in 

the skin, so there are taste buds in 
the tongue. They are located on 
the sides of the elevations or papillae 
of the tongue. The largest of these 
are located in two rows near the back 
of the tongue and other smaller ones 
are scattered over the tongue. (Fig 
230.) A cross-section of one of the 
large papillae is shown in Fig. 231. 
The taste buds are located in the epi¬ 
thelial layers in the sides of the pa¬ 
pillae, and are seen to consist of long 
spindle-shaped cells (1 and 2, Fig. 
232) with their points coming to¬ 
gether at the taste pores (P). Among 
some of these cells (2) arise fibers of 
the nerves of taste (N), branches from certain cranial nerves. 
Substances are tasted by being taken up by the taste cells 
of the taste buds, which in turn stimulate the nerves of taste. 
Only liquid substances can be tasted because only these can 
be absorbed by the taste cells. The sense of taste is use¬ 
ful in helping to guide animals in the selection of their 
food and to stimulate the digestive juices. How does 
saliva help us to taste starchy food? (See experiments, 
page 154.) 

Smell. —Only sweet, sour, bitter and salty substances can be 


TNROAT 



Fig. 230. The Tongue. 




The Special Senses. 


303 


tasted. We distinguish among flavors largely by the sense of 
smell. Closing your eyes and holding your nose, let some one 


FIG. 231 FIG. 232 



Fig:. 231. Section of a large papilla of the tongue, showing taste buds 
(B) and nerve of taste (N). 

Fig. 232. A taste bud of 231 more enlarged; P., taste pore; 2, “taste” cell; 
1, supporting cell. 


OLFACTORY NERVE 


lay on your tongue suc¬ 
cessively a slice of apple, 
of potato and of onion. 

Can you distinguish them 
by taste alone? In order 
that the nerves of smell 
may be excited, gases or 
tiny particles floating in 
the air must enter the 
nasal passages. Study Fig. 

133 and note two ways by 
which odors may pass into 
the nasal passages. The 
nerves of smell make up 

the pair of first cranial or olfactory nerves. (Figs. 233 and 
210.) The branches of this nerve are spread out over the ir- 



Fig. 233. The nerve of smell at the base 
of the brain and the branches in the 
upper part of the left nasal passage. 










304 


The Human Body and Its Enemies. 


regular inner surface of the nose (Fig. 233) and pass 
through holes in the base of the skull to make up the olfac¬ 
tory nerves. 

The end cells of smell are located in the mucous membrane 
of the nasal cavities. Here are two kinds of cells; long epi¬ 
thelial cells (Fig. 234) and spindle-shaped cells with a long 
projection at one end and nerve fibers at 
the other. The cells with the nerve fibers 
are the “smelling cells.” Particles of 
matter are sniffed in with the air and, 
striking the ends of the smelling cells, 
stimulate them. The impulses are passed 
on to fibers of the olfactory nerves, and 
thence to the brain. Have you any idea 
Fl ceHs 23 from S tht ni mu- how tin y a P article may stimulate the 
the S na?a e i m pa r ss n a e ge. of smelling cells? Can you explain how a 
dog can find his master through a crowded 
street, even after the master has passed some time before, and 
out of sight of the dog? Smell is a useful sense in enabling us 
to detect harmful gases in the air, such as fuel gas and odors 
that indicate disease breeding objects in the surroundings. Foul 
odors are disagreeable because Nature intends that human 
beings must be cleanly and healthy. How is the nose a 
good detector of impure air in a schoolroom ? 

Summary. 

The special senses are those of touch, taste, smell, hearing, 
and sight. Certain organs can be designated as the organs of 
the special senses: the skin, the tongue, the nose, the ears and 
the eyes. In these organs are special cells, the “end cells,” 
whose duty it is to take up the stimuli, such as objects strik- 












The Special Senses. 


305 


ing the skin (touch), substances in solution (taste) or in the 
air (smell). The end cells magnify these stimuli and pass 
them on to the nerve fibers leading to the cerebrum. Here the 
stimuli are translated into sensation, and we feel, taste, smell, 
etc. The end cells of touch are in touch buds in the skin; but 
temperature nerves end in scattered cells. The end cells of 
taste are in taste buds of the papillae of the tongue and the end 
cells of smell are in the upper part of the nasal passages scat¬ 
tered among the cells of the mucous membrane. In every case 
the nerve impulse must be carried to the cerebrum to result in 
sensation. 


Questions. 


1. Mention some general sensations. 2. What is the use of these? 
3. Why can you not designate organs of general sensations? 4. 
Name the special senses and give the organ of each. 5. What is the 
function of the end cells in the sense organs? 6. What other condi¬ 
tions besides end cells must there be before we can experience sen¬ 
sations? 7. Illustrate this in the case of sight. 8. Where are the 

end cells of touch located? 9. What parts of the skin have you 

found to be most sensitive to touch? What is meant by temperature 
sense? 11. How can you show that there are special nerves to 

carry impulses of heat and cold? 12. What is the function of the 

papillae of the tongue? 13. Where are the end cells of taste lo¬ 
cated? 14. Of smell? 15. Why are taste and smell easily confused? 
16. What are the uses of (a) the sense of touch? (b) Of smell? 
(c) Of taste? 


CHAPTER XLIII. 


Hearing. 

Taste is a more delicate sense than touch, and smell is more 
delicate than taste. Hearing is still more delicate. What is 
it we hear? Sound, you say. When two objects are struck 
together, as when a bell is rung, invisible waves of air are pro¬ 
duced, called sound waves, which radiate out from the center 
in all directions as do 
waves of water on the sur¬ 
face of a quiet pool when 
a rock is thrown into it. 

The sound waves are 
caught up and transmitted 
to certain cells in the ear 
where the nerve of hearing 
(auditory nerve) ends. 

Since the hearing organ is 
so delicate, it is encased 
for protection in the bones 
of the skull. 

The Outer Ear. —The 

ear consists of three parts 
or regions: the outer, the 
middle and the inner ear. The outer ear consists of the shell¬ 
shaped outer part that serves to collect the sound waves; and 
a canal, the auditory canal (Fig. 235) that conducts 
the sound waves to a membrane, the tympanum or 



Fig-. 235. Diagram of a section of the 
ear, showing outer, middle and inner 
ear. 







Hearing. 


307 


ear-drum, at its bottom. The tympanum may be likened to 
a drum-head: when the drum-head is beaten it vibrates: so, too, 
the tympanum vibrates when sound waves strike it. Hear¬ 
ing would be imperfect without the tympanum. To protect it 
from injury, the auditory canal is crooked, and has glands 
in it that secrete yellow bitter wax which keeps insects awaj 
from the tympanum. Under no circumstances should anyone 
try to remove objects from the depths of the canal with any 
hard instrument for fear of injury to the tympanum. 

The middle ear is likewise hollow, and communicates below 
through the Eustachian tube (Figs. 233 and 235) with the 
pharynx and through this with the outside world. Thus air 
can get to the tympanum from both sides. Do you see why 
this is? Your physical geography teaches that atmospheric 
pressure varies with the weather. If the pressure were greater 
or less on the outer than on the inner surface of the tym¬ 
panum, this organ would be stretched, causing pain. Indeed, 
during a cold, the Eustachian tube may become stopped up and 
earache result. Sometimes an ear-drum is broken by a loud 
sound like the report of a cannon. If the Eustachian tube were 
in good condition such an accident would probably be pre¬ 
vented by simply opening the mouth when the cannon is dis¬ 
charged. 

How, then, do the sound waves cross the middle ear? At¬ 
tached to the tympanum is a bridge of three bones, named from 
their shape, hammer, anvil and stirrup. (Fig. 235.) These bones 
are even more important for hearing than the tympanum. The 
hammer is attached to the tympanum, the anvil is in the mid¬ 
dle and the stirrup is next to the inner wall of the middle ear. 
These bones vibrate with the vibration of the tympanum, and 
as they do so the stirrup “knocks” at the door of the inner 
ear, causing corresponding vibrations in this organ. 


308 


The Human 1 Body and Its Enemies. 


The inner ear is made up of two parts: the cochlea and the 
semi-circular canals. Of these only the cochlea functions in 
hearing, for therein are the nerve endings that take up 
sound waves. 

Cochlea means snail-shell. (Fig. 236.) As in a snail-shell, 
the hollow winds round and round to the top, so in the cochlea, 
a canal winds round two and one-half times to the top and 
then turns back. There are really two canals, communicating 
at the top and separated all the way by a partition. Now, on 
this partition there 
are cells with tiny 
hairs: these are 
the end cells of 
the auditory nerve, 
the cells that catch 
up sound waves 
and transmit the 
impulse to the au- 
ditory ner ve, 
which carries it to 
the cerebrum as 
sensation of sound. 

The canals are filled with a liquid, a kind of lymph. The way 
the sound waves are made to stimulate the hearing cells is inter¬ 
esting. The air waves strike the tympanum and set it in vi¬ 
bration; this causes the hammer, anvil and stirrup to vibrate. 
The stirrup knocks against the “oval window’’ (0, Fig. 236) of 
the cochlea, setting in vibration the lymph in the canals; the 
waves of this liquid pass through one canal to the top of the 
cochlea, then down the other and finally die out when reaching 
the end of the canal at the “round window” of the cochlea. 
(R, Fig. 236.) This principle is shown in Fig. 237, which rep- 





Hearing. 


309 


resents the cochlea uncoiled and stretched out. The arrows in¬ 
dicate the path of the waves. When the lymph is in motion in 
the canals, it rubs over the hairs of the hearing cells (D, Fig. 
236) and starts impulses that are carried to the brain by the 
auditory nerve fibers and there interpreted as sound. 

The semi-circular canals are not used in hearing, but they 
have an important use in that they act as spirit levels and in¬ 
form us (unconsciously, however,) when we are about to fall 
over. They, too, are filled with a liquid and their walls 
contain cells 
with project¬ 
ing hairs. In 
these ce 11 s 
certain fibers 
of the audi- 
tory nerve 
end. When 
the body or 
the head is 
moved in any 

direction the liquid moves in one or the other of the canals. 
Of course, in the daytime a person can see with his eyes what 
position he is in, or he can see when he is about to fall over; 
but with the semi-circular canals he feels it much more quickly 
and can, by reflex action, right himself at once. 

Summary. 

The stimuli from the outside that cause us to hear are waves 
or vibrations of air. These are collected by the outer ear and 
directed to the ear-drum, which is thus made to vibrate. The 
sound waves are carried across the middle ear by a series of 



Fig-. 237. Diagram showing: passagre of waves of sound 
through the ear; AC, auditory canal; T, ear drum; 
ET, Eustachian tube. 







310 


The Human Body and Its Enemies. 


three ear bones, the inner one of which, the stirrup, knocks 
against the opening of the inner ear. It is in the cochlea of 
the inner ear that the auditor nerve reaches the end cells that 
catch up the waves of sound. These cells are upon the par¬ 
tition of the spiral canal which winds around the cochlea. 
The wave travels in the liquid with which the cochlea is filled 
to the top of the cochlea on one side of the partition and 
comes back on the other side. As it travels through the coch¬ 
lea it stimulates the end cells to which the auditory nerve 
fibers are attached. The impulse is carried to the brain, and 
thus we hear. 

The semi-ciruclar canals also contain a liquid and end cells 
with nerve fibers. The canals are so placed that whenever we 
change our position the liquid in one or the other of the ca¬ 
nals moves. The canals thus help us to maintain the balance 
or equilibrium of the body. 

Questions. 

1. What is air composed of? (Chapter XXVIII) 2. How are 
sound waves produced? 3. Name the divisions of the ear. 4. Name 
the parts of the outer ear and tell the function of each. 5. What 
separates the outer from the middle division? 6. How may the ear¬ 
drum be injured? 7. How is it protected? 8. How does the middle 
ear communicate with the outside air? 9. Why is this so? 10. How 
do sound waves cross the middle ear? 11. Name the two parts of 
the inner ear. 12. Which of these functions in hearing? 13. 
Where are the end cells of hearing? 14. How do the sound waves 
reach these cells? 15. Where do the impulses pass from these cells? 
16. What is the use of the semi-circular canals? 


CHAPTER XLIV. 


Sight. 


rtERve 


In the sense that the ears are the organs of hearing the 
eyes are the organs of sight. As the ears are so constructed 
as to receive stimulations of sound waves and start these stim¬ 
ulations to the cerebrum, so the eyes are so built as to re¬ 
ceive from light waves stimulations that are passed on to 
nerves going to the cerebrum. 

Sound waves are vibrations of 
air, and without air there 
could be no sound. But light 
travels far beyond the limits 
of the atmosphere, for it comes 
to us from the sun, moon and 
stars. Air seems to us to be 
very light and thin, but it is 
really very heavy and dense 
when compared with the substance that carries light. This 
substance, is called ether. It pervades all space and waves of 
ether are light waves. Although we cannot see the waves of 
ether we must imagine them to be like the waves rippling 
across the surface of a pond of water. The eye has end-cells, 
sensitive to these delicate waves of ether, and branches of 
the nerve of sight (optic nerve), to carry the impulse to the 
brain. In this chapter we shall study how we see. 

Protection of the Eye. —The eye cannot be put away inside 
the bones like parts of the ear, but it, too, is protected. It is 



Pigr. 238.—The muscles that move 
the eyeball. 


312 


The Human Body and Its Enemies. 


set back in an orbit or hollow of the skull (Fig. 183), so that 
a fall or a blow on the face will not injure the eye. Again, 
two flaps of muscle, the eyelids, can be pulled over the eye 
to protect it against objects flying toward the face. (Study 
the action of the eyelids from the standpoint of reflex action, 

page 278). The eyelids are 
aided in their work of keep¬ 
ing out dust and dirt by pro¬ 
truding hairs on their edges, 
the eyelashes. 

You have noticed that 
persons and animals wink at 
intervals. The purpose of 
this is to distribute over the 
eyeball a fluid secreted by 
the tear glands, for the sur¬ 
face of the eyeball must be 
kept moist. The tear glands 
lie along the outer side of 
the eye and the tear is emp¬ 
tied on the under side of the upper eyelid. (Fig. 239.) The 
tear is usually carried off by certain tear ducts that lead to 
the nose; only in weeping do the eyes “overflow.” The se 
cretion of the tear glands is regulated by nerve fibers from 
the cranial nerves and, as you would expect, from the sympa¬ 
thetic system. One of the two openings of the tear duct can 
be seen in the center of a little elevation or papilla on the 
edge of the lower eyelid, near the inner corner of the eye. 
That the tears do not always run over the edge of the eyelid 
is due to the fact that there is a row of oil glands which 
empty their fatty secretion on the edge of the lid, thus pre¬ 
venting the tears from running over. During sickness these 









Sight. 


313 


glands secrete too large an amount of oil, which, on drying 
and becoming hard and yellow, may glue the eyelids together. 

Observation and Practice Work.—Using a mirror find the papilla 
on the lower eyelid as described above. Pull the eyelid down a 
little and the papilla with the opening to the duct will come to 
view. Make a drawing of the eye with the eyebrows, lids, eye¬ 
lashes and other parts. Name them in the drawing. 

How the Eyeballs Are Moved. —Looking at a sheet of paper 


FJG. 240 FIG. 241 



Fig-. 240. Section of the eyeball with parts named. 

Fig - . 241. A part of Fig. 240 enlarged, to show attachment of lens. 

Fig. 242. The part A of the retina in Fig. 240, much enlarged to show the 
“seeing” cells of the retina. 


you will notice that, without turning the head, you can glance 
from the center to the right and left edge, to the top and 
bottom edges and to the corners of the paper. It takes six 
muscles (three pairs, Pig. 238,) to move each eye, and it takes 
three cranial nerves to supply these muscles and to regulate 











314 


The Human Body and Its Enemies. 


their action. The two eyes move together, since the motor 
nerves send branches to corresponding muscles of each eye. 

The form and inner structure of the eye can best be de¬ 
scribed with the aid of diagrams. The eyeball is almost spher¬ 
ical in shape, bulging a little in front, as shown in Fig. 240. 

The supporting layes of the 
eyeball are two in number: the 
outer or sclerotic coat, and the 
inner, or choroid. The “white 
of the eye” is a part of the 
sclerotic, as is also the transparent cornea, through which the 
black pupil and the colored iris can be seen. The choroid con¬ 
tains dark pigment so as to darken the inside of the eye; for 
the eye is a miniature camera or kodak, a dark box with only 
a small opening in front for the light to enter. This opening 
is the pupil, which is surrounded by a colored ring, the iris, 
a part of the choroid coat. A person’s eye is said to be blue 
or brown if the iris is blue or brown. The iris regulates the 
amount of light to be admitted to the eye. In bright light the 
pupil is small (Fig. 244) ; in the dark the pupil is large (Fig 
243), There are muscles in the iris that regulate the size of 
the pupil, and these muscles are regulated by cranial and 
sympathetic nerves. Their action is reflex and involuntary. 

Observation Work.—At night, examine the size of the pupils of 
the eyes after having been in the dark for some time. Then ex¬ 
amine them after having been in the light, perhaps looking at a 
white sheet of paper for ten or fifteen minutes. (See Figs. 243 
and 244.) Examine a cat’s eye at night and again in the daytime. 

The Lens. —Immediately behind the iris is the lens. This 
is a most important organ in enabling us to see clearly and 
is to the eye what the glass lens is to the camera. The eye¬ 
ball is filled with a clear watery fluid (the aqueous humor, 



Figs. 243 and 244. The pupil of the 
eye, large and small. 


Sight. 


315 


Fig. 240) in front of the iris, and with a clear, jelly-like mass 
(the vitreous humor) behind the lens. 

The Retina. —Waves of light enter the pupil, pass through 
the lens and are distributed over the inside wall of the eye. 
Where, then, are the sensitive cells and their nerve fibers that 
catch up the light waves? These cells are located in a coat of 
the eye called the retina, inside of the choroid. (Fig. 240.) 
This layer of sensitive cells occupies a position similar to that 
of the sensitive film or plate in a camera. 

There are, consequently, three coats of 
the eyeball: the sclerotic, mainly for sup¬ 
port ; the choroid, mainly to absorb the 
excess of light, that is, to make the eye¬ 
ball dark inside; and the retina as the 
layer sensitive to light waves. Fig. 242 
represents a section of the retina, much 
enlarged. The sensitive cells are ^‘.rods 
and cones,” (so called from their shape) 
and stand pointing toward the choroid 
layer. More or less closely connected with these are nerve 
fibers from the optic nerve. (Fig. 210.) Light waves strike 
the rods and cones and cause nerve impulses in the fibers of 
the optic nerve. These, on reaching the nerve ceHs of the 
cerebrum, cause the sensation of sight. 

The Refraction of Light. —Rays of light tend to travel in 
a straight line. But when, after passing through air, they 
strike the surface of water or glass or the transparent parts 
of the eye, the rays are bent suddenly out of their course. We 
say they are broken, or refracted. This refraction can be 
illustrated by the following experiments: 



Fig-. 245. A pencil looks 
bent or “broken” 
when immersed in 
water. 









316 


The Human Body and Its Enemies. 


Experiments on Refraction.— (1) Place a pencil into a tumbler of 
water and note that the pencil looks broken, as shown in Fig. 245. 
(2) Into a tin cup place a coin and have ready a quantity of clear 
water. Place the eye as shown in Fig. 246, so that the coin will 
be just out of view. Now cautiously pour water into the cup. Note 
that the coin gradually comes into view as the water level rises. 

Fig. 247 gives the expla¬ 
nation of this. Rays of 
light between the bottom 
of the cup and the eye 
(E) are refracted at the 
surface of the water, A, 
where water and air meet, 
as, for example, ray ADE. 
Therefore the coin, A, is 
in full view, although not 
in direct line, and seems to be raised above the bottom of the cup, 
as at D. (3) To show how a lens refracts the rays of light, hold 
a glass (a magnifying glass or a convex lens from a pair of spec¬ 
tacles) in the sun, using it as a “burning glass.” The rays of sun¬ 
light are refracted by the lens and turned together to a focus. 



How the Image Is Thrown Upon the Retina. —The rods and 
cones that catch up the rays of light are very tiny. In order 
to see sharply and clearly a single rod or cone must receive 


the light from a single 
tiny point of an object. 
To make clear how an im¬ 
age is formed on the ret¬ 
ina we may begin with a 
simple thing, for instance, 
a small spark the size of 



Fig. 248.—The rays of light from a single 
point would be scattered over the 
retina if there were no cornea or lens. 


a period used to punctuate this page. The spark gives off 
rays of light in every direction, for it can be seen from all 


sides. But only those rays would reach the retina which 


pass through the pupil. Thus of all the rays of light repre¬ 
sented in Fig. 248, which radiate from the spark (S), only 
















Sight. 


317' 


A, B and C reach the retina. Now, if the light rays would 
enter the eye unobstructed (as represented in Fig. 248) the 
rays A, B and C would strike the retina at a, b and c. So 
with all other rays between them. There would be so many 
images of the spark on the retina that we would see the spark 
as a large round spot. Of 
course, if the pupil were 
made so small that only 
ray C could enter, there 
would be but one image, 
c; but this would not be 
bright and strong. It is, 



Fig. 249. The cornea and the lens focus¬ 
ing rays of light to a point. 


therefore, desirable 
that all of the rays 
that strike the eye 
in front of the pupil 
(A, B and C) should 
fall on one point, c, 
as in Fig. 249. This 
is brought about by 
the convex surfaces 
of the cornea and 
the lens which refract the rays and turn them together to a 
point or focus on the retina (c, Fig. 249.) Collecting the rays 
• of light and bringing them to a focus is called focusing. 

So it is with all the many rays of light that pass out from 
every object. In Fig. 250 the rays from the point A, on the 
head of the arrow, are focused on point a of the retina; those 
from point B on the feather of the arrow are focused at b on 
the retina. Each part of the arrow is thus clear-cut on the 
retina. The images of objects are thrown on the retina in¬ 
verted. In order, then, that the image of the object may be 



Fig. 250. Every ray of light from any one 
point of an object is focused on the retina. 
This causes a clear image of the object 
to form on the rods and cones of the retina. 









318 


The Human Body and Its Enemies. 


clear, the cornea, the lens and the entire eyeball must be of 
the right shape. Such is the case in the normal eye. 

Observation Work.—Look out of the window into the distance. 
Now hold up your hand in front of your face and continue looking 
into the distance between the fingers. The hand is not seen clearly 
—it is blurred. Again, hold your finger one foot from your face 
between your eyes and the landscape. Look at your finger. If you 
see the finger in clear outline the objects of the landscape are 
blurred. This is due to the action of muscles changing the shape 
of the lens, as will be noted below. 

Accommodation. —As shown in the experiment just made 
there must be something in the eye which must be “set” for 



Fig. 251. Diagram to show the lens is changed for far or near vision. 


seeing far or near. That “something” is the lens, which “ac¬ 
commodates” the eye for far or near sight. For seeing near 
objects, the lens must bulge out in front, that is, it must be 
more convex. It is made so by muscular effort. Fig. 241, 
which is part of Fig. 240 more enlarged, shows that the lens 
is attached by a ligament (Lig) to a process (ciliary process) 
in the wall of the eyeball. The ligament is a complete circle, 
of course, and there is a whole circle of ciliary processes. 
Muscles (ciliary muscles) are so attached that when they con¬ 
tract, the ciliary processes are pulled toward the lens and the 



Sight. 


319 


ligament holding the lens slackens. The result is that the lens, 
being elastic, assumes a more convex form. (Fig. 251.) The lens 
is not stretched and flattened by muscular effort, as is some¬ 
times thought, but made to bulge or thicken. When the ciliary 
muscles relax, the ligament of the lens resumes its pull and 
the lens again takes on the flatter shape for seeing at a dis¬ 
tance. It is important to note that it requires muscular ef¬ 
fort for seeing close by,'as, for example, in reading and sew¬ 
ing. Study carefully Fig. 251. 

Experiment to feel that muscular effort is needed for near 
vision—look into the distance. The lenses of your eye are now ac¬ 
commodated for far vision. The ciliary muscles are at rest. Now 
bring the finger up before the eyes and remove the attention from 
the distance to the finger, noting carefully the feeling in the eye¬ 
ball as the accommodation to near vision is being made. 

The Normal Eye. —In a normal eye (1) the eyeball is of the 
right shape; (2) the iris properly regulates the amount of 
light that enters the eye; (3) all of the parts through which 
light has to pass are transparent (name them) ; (4) the lens 
and cornea have a smooth, regular surface, without irregulari¬ 
ties; (5) the lens is elastic, responding readily to the effect of 
the ciliary muscles, or springing back into the resting posi¬ 
tion. 

The Defective Eye. —Common imperfections in vision are due 
to defects in regard to one or more of the points just enu¬ 
merated. The image must come to a focus exactly on the 
retina (Fig. 250), or the image will not be distinct. 

In near-sightedness the image comes to a focus before 
reaching the retina (Fig. 252), and the same rods and cones 
receive rays of light from different parts of the object, thus 
confusing the image and making it dim and blurred. Such an 
eye would be helped by concave lenses set into spectacles, for 


320 The Human Body and Its Enemies. 

such lenses would spread the rays of light and prevent their 
coming to a focus too soon. (Fig. 253.) Near-sightedness is 
usually due to the fact that the eye is too long, that is, the 



Figs. 252 and 253. In short-sightedness the eyeball is too long. This may 
be overcome by a concave lens. 


the distance from the cornea to retina is too great. (Fig. 252.) 

Far-sightedness is due to the opposite cause from that of 
near-sightedness; it is due to the eye’s being too short from 
cornea to retina. (Fig. 254.) In such an eye the image reaches 
the retina before the rays of light have been brought to a 



Figs. 254 and 255. In far-sightedness the eyeball is too short. This de¬ 
fect is overcome by wearing- convex glasses. 

focus. A person suffering with far-sightedness should 
wear glasses with convex lenses, for these bring the rays of 
light together and help the lens of the eye to focus the 
rays on the retina. (Fig. 255.) The wearing of spectacles is 
not a fad, but is based on scientific facts. Many headaches 
are due to imperfect eyesight that might easily be corrected 
with glasses.* 


♦Most old persons are far-sighted. The tissues of the lens be¬ 
come hardened and cannot be accommodated for clear vision. This 
is the reason that most older persons can use one another’s glasses 



















Sight. 


321 


Astigmatism is a defect of the cornea and the lens, in which 
either or both- have irregularities or uneven places in their 
curved surfaces. This is a common cause of imperfect vision 
with children, and should receive prompt attention. A pupil 
poor in reading, but good in other studies, probably has some¬ 
thing wrong with the eyes. 


CARE OF THE EYES. 

A study of the anatomy of the eye and the physiology of its 
parts enables us to study intelligently the hygiene of the eye. 

Rest. —Since the ciliary muscles contract to accommodate 
the lens for ‘‘near work,” such as reading or sewing, it is 
necessary that they be rested from time to time. This is, of 
course, easy to do by simply looking into the distance. This 
relaxes the muscles and has the same effect on them as 
“relaxation” has on the muscles of the arms and legs. 

The size of type used in printing the matter which you read 
is an important consideration. If the type is too small the 
strain on the eyes is very great. It does not pay to purchase 
even a cheap book with poor type. The size of the letters in 
the Primer and first reader used in your school is probably 
the best size for a beginner. This book is printed in clear 
type of the right size for most people. 

The Intensity of the Light. —For reading or other close 
work with the eyes the light should be neither dim nor very 


with comfort. Look at a printed page through an old person’s 
spectacles and you will see how the page looks to the person when 
not using his glasses; you will also get an idea of what is meant 
by a blurred image. 



322 


The Human Body and Its Enemies. 


bright. If too dim the pupil of the eye becomes so large as to 
cause the letters of the printed page to be less clear and dis¬ 
tinct. It is a great mistake to read at dusk without artificial 
light. Neither should the light be too bright. If your eyes 
are strong, now you are fortunate and should not neglect 
their care. 

Direction of the Light. —The best rule to follow is to have 
the light pass over the left shoulder on to the printed page. 
Never should the light come from the front. In a school room 
the front windows, if there be any thus wrongly placed, 
should be darkened. The main light should come from the 
left. The windows should be placed high, even touching the 
ceiling, for it is the light from above falling on the desks 
which is best in the school room. If shades are needed to 
keep out the direct rays of the sun, they should be of the ad¬ 
justable kind, so as to allow some light to enter from the top 
if possible.* Shades pulled down on a sunny day should be 
raised on a cloudy day. Watch your school room and keep 
the lighting right. When reading by artificial light do not al¬ 
low the light to shine directly into the eyes. It is well to 
shade the light or to place a shade over the eyes to protect 
them. 

Steady Light. —A flickering light, such as that of a candle, 
or a simple gas jet without a mantle, is hard on the eyes. 
Reading on trains should also be avoided. 

Spectacles. —It has been explained how spectacles correct 
the defects in vision caused by abnormally long or short eye¬ 
balls, by irregularities of the cornea or lack of elasticity of the 
lens. Many pupils are backward in school on account of de¬ 
fects in vision, which could easily be corrected by the use of 


See footnote, page 203. 



Sight. 


*323 


glasses. Teachers should be on the lookout for such cases and 
parents should consult a competent oculist concerning the 
child’s eyes when there is the slightest suspicion of optical 
defects. 

Cinders in the Eye. —The eyeball is covered and the eyelids 
lined with a very delicate membrane easily injured. The 
presence of hard, sharp particles, such as cinders or sand- 
grains, irritates this membrane and causes inflammation of 
the eyeball and of the lid. The foreign particles should be 
removed with the corner of a clean handkerchief. Disease 
germs are also likely to enter the eye and cause inflammation. 
The eye should not be rubbed with the fingers, as by this 
means germs are often transferred to the eyes. 

Trachoma (also called granulated lids) is the worst com¬ 
municable disease that affects the eyes. It is not very common 
in this State, and yet it is fairly well distributed over the dif¬ 
ferent counties. It causes sore eyes, and later, scarring under 
the lids, so that they pucker up and do not fit the eyeball. The 
cause of trachoma is not known, but we do know positively 
that it is contagious. It is communicated by the matter or se¬ 
cretion from the eyes, but, of course, this matter must in some 
way get into the eyes of the new victim. The disease may be 
spread by public towels or by pencils borrowed from children 
that have sore eyes. When we have as many gnats and flies 
as we had in 1902, these may light on the eyes of one indi¬ 
vidual, pick up a few drops of the infected fluid, and carry 
it to the eyes of another individual. For this reason, as well 
as for many others, our houses should be screened to keep the 
insects out. 

The ordinary “sore eyes,” which merely causes the eyes 
to stick together for a few days, is another contagious eye 
disease which is called “pink-eye.” This is carried from one 


324 


The Human Body and Its Enemies. 


child to another in the same way as the trachoma. In 1902 
there was an epidemic of this disease in Texas due to the gnats 
and flies. We do not often have so many insects as we had 
in 1902, but we have the public towel with us at all times, and 
we should be on our guard against that. A good substitute 
for it is the sanitary paper towel, which can be bought at about 
one-fourth cent each. (Fig. 181.) 

Summary. 

The eye, or seeing organ of the body, may be likened to a 
camera. Like the camera, the eye is a dark box, the choroid 
coat serving the purpose of the black paint in the camera. 
There is an opening, the pupil in the eye, to admit the light. 
The size of this (and thus, the amount of light entering the 
eye) is regulated by the iris. The sensitive film is the retina, 
containing the rods and cones, which are the sensitive end 
cells, or “seeing cells,” connected with fibers of the optic 
nerve. There is, too, a clear convex lens, which, with the 
clear convex surface of the cornea, serves to focus the light 
rays on the retina as the glass lens of the camera focuses the 
light on the sensitive film. 

For far and for near vision a different focus is required. 
This change of focus is brought about by a change in the con¬ 
vexity of the lens. When the ciliary muscles contract they 
bring the ciliary processes nearer the lens, thus allowing the 
elastic lens to bulge out. When the muscles relax the lens 
is brought back to the flatter shape. We can rest the eye from 
continued close work by occasionally looking off into the dis¬ 
tance. Short-sightedness, far-sightedness and astigmatism are 
common defects in vision, due to the imperfection of the focus¬ 
ing apparatus of the eye. They may be corrected by wearing 
the proper glasses. 


Sight. 


325 


We should take the best of care of these wonderful organs, 
the eyes. We should be observant about the direction and the 
quality of the light. We should not touch the eyes with our 
fingers or with unclean objects for fear of transferring germs 
to the moist, delicate membrane covering the eye. 

Questions. 

1. What are sound waves? 2. Light waves? Why cannot the 
eye be put away in the skull bones as is the inner ear? 4. How is 
the eye protected against blows? 5. Against dust? 6. Against 
drying out? 7. How are the tears ordinarily kept from flowing 
over the edge of the eyelids? 8. Point to your own tear glands. 9. 
Why do we have to blow our noses when we begin to cry? 10. 
How many muscles move the eyeball? 11. How many nerves are 
represented in Fig. 210 as passing to the eyeball? 12. From a 
section drawn on the blackboard after Fig. 240, point out the 
three coats of the eye. 13. What , is the function of each coat? 
14. From what part of Fig. 240 is Fig. 241 an enlargement? 15. 
How does the pupil grow larger and smaller? 16. Why does it 
change in size? 17. Why cannot owls see well in daylight? 18. 
Where is the cornea? 19. The lens? 20. The iris? 21. How is 
the lens held in place? 22. Why can we not see all the rays of 
light coming from a given point? 23. What is meant by refrac¬ 
tion? 24. Describe two experiments to illustrate refraction. 25. De¬ 
scribe focusing. 26. Why do rays of light have to be focused on the 
retina? 27. How are they focused? 28. How is the eye accommo¬ 
dated for seeing near objects? 29. Draw Fig. 251 on the board 
and explain the use of all the parts shown. 30. How can you 
prove that it requires muscular effort to accommodate the eye for 
seeing a near object? 31. How can you rest your eyes at intervals 
when engaged in close work? 32. Mention the common defects of 
the eye. 33. Describe the near-sighted eye. 34. The far-sighted eye. 
35. Why do people usually become far-sighted with age? 36. What 
is astigmatism? 37. What can we do for these common optical de¬ 
fects? 38. What can you say as to the intensity of the light in 
reading and sewing? 3 9. The direction of light? 40. How may 
contagious diseases of the eye be avoided? 


CHAPTER XLV. 


Accidents and Emergencies. 


It is not often that accidents occur when we are expecting 
them; this is only another way of saying that we are usually 
unprepared when accidents occur. It is possible, however, 
for us to prepare ourselves to a certain extent, so that we shall 
not be entirely helpless in the face of emergencies or sudden 
happenings. 

Examination of the Injured Person. —The first thing to do 
when anyone is injured is to look him over and see whether he 
is losing blood and whether he is getting his breath. If he is 
not bleeding very much, and is breathing, we may rest assured 
that there is no pressing need for immediate action. 

Severe Hemorrhage. —If, however, the injured person is 
bleeding profusely, something must be done at once. In case 
of large hemorrhage, that is, if the patient is bleeding as much 
as a teacupful every minute or two, it is absolutely necessary 
to stop the hemorrhage on the spot. There is no time to hunt 
up medicines, or clean bandages. Under these circumstances, 
the cleanest cloth that can be found must be pressed into 
and around the wound. If it be pressed tightly, with all one's 
strength, it will staunch almost any hemorrhage. After 
the bleeding is hurriedly stopped, or at least diminished in this 
way, it is time to look around for some more satisfactory way 
of keeping down bleeding till assistance can arrive. Some¬ 
times it is necessary to hold the fingers pressed into a wound 
for an hour till the surgeon can reach the patient. If the 


Accidents and Emergencies. 


327 


hemorrhage is from an extremity, that is, from an arm or leg, 
a tight bandage, such as a handkerchief wrapped around the 
limb, between the wound and heart, will stop the bleeding. A 
tight bandage should not be left on a limb for more than half 
an hour or it may cause gangrene. 

Trifling hemorrhage should be stopped by placing a clean 
white cloth over the wound and making gentle pressure. Usu¬ 
ally, binding the cloth onto the wound will prevent a return 
of the hemorrhage. 

Cuts and other open wounds should not be washed with water 
unless the water is pure. Boiled water is always free from 
germs. A reliable antiseptic or disinfectant should be applied 
to wounds of this character, and they should be covered with 
clean white cloths, preferably cloths that have been boiled and 
dried without being handled. Disinfectants have _ been de¬ 
scribed in Chapter XVI. Usually it is not wise to employ a 
solution of carbolic acid as a permanent dressing, unless the 
acid and the water are mixed thoroughly; and it takes a good 
light to decide the question. 

Gangrene has been produced 
in numerous instances by 
dressing wounds in moist 
carbolic dressings. 

Broken bones are painful, 
and may in certain cases be 
dangerous. The worst thing 
that can happen after a frac¬ 
ture has occurred is for the 
bones to protrude or stick out through the skin. When they 
do so, they are likely to become infected by germs, especially 
the tetanus or lockjaw germ. The bones should therefore be 
handled carefully to avoid opening the skin. The picture shows 



Fig. 256. A pillow and two boards 
make a good tempoiary brace of 
splint for a broken limb. The pil¬ 
low is made into a trough, the 
limb is placed in this trough, and 
the boards are adjusted and held 
in place by several handkerchiefs 
or other bandages. 


328 


The Human Body and Its Enemies. 


a pillow-splint that can be applied when no surgeon is at hand. 
This splint is suitable for fracture of arm or leg. 

Tetanus or Lockjaw. —The tetanus or lockjaw germ is one of 
the worst germ enemies we have, and it would pay us well to 
study it. This germ lives outside the body oftener than inside. 
It is not like the typhoid germ, which refuses to multiply ex¬ 
cept in the human body. The tetanus germ lives in the 
ground, especially around gardens and horse lots. It practi¬ 
cally never harms the human body except when introduced 
through an open wound. So far as we know, swallowing 




CONTAINING; A OPENED 

TETANUS GCMMO T&TANU-& CrEHM-S can't 
2 * ^ UlVfc IN A I A 


Fig. 257. The middle picture shows how the tetanus germs are closed off 
from the air when the skin heals too rapidly. The only safe thing to 
do is to open up the abscess and let in the air. 


the tetanus germ never hurts anyone. The fact is that the te¬ 
tanus germ cannot live in the air; it has to be shut off from the 
air. Supposing that the wound has been made by a rusty nail, 
after the skin swells a little and closes the hole made by 
the nail, the germ is down under the human skin, and is shut 
off from the air. You have noticed that healing of the skin 
often occurs, even though there are germs and pus down deep 
under the skin. 

Tetanus Is Almost Incurable. —A remarkable thing about 
this disease is that after it once develops the doctors can do 
very little toward healing or curing it. Lockjaw causes the 
most terrible spasms all over the body. The locked jaws are 


Accidents and Emergencies. 


329 


the least part of the disease. If we are to save one’s life 
after he has thrust a nail into his foot, we must act before the 
disease develops. Usually it takes tetanus about a week or 
ten days to develop after the wound is received. The proper 
treatment is to open up the wound and let the air get down 
into the depths of it. This is shown in Fig. 257. If there 
is any doubt about the air getting entirely into the depths of 
the wound, tetanus antitoxin should be given. If these pre¬ 
cautions are neglected, and if the tetanus once appears, 
all the powers on earth cannot with any certainty prevent 
death. Over three-fourths of all cases of tetanus die. The 
antitoxin is good for prevention, but cannot be relied upon 
to cure after the disease once develops. 

All Narrow and Deep Wounds Are Dangerous. —From what 
has been said, you can see that all narrow deep wounds are 
especially dangerous, because the skin closes up and shuts out 
the air, making it possible for the tetanus bacterium to live. 
Powder burns made by the little toy pistols and by firecrack¬ 
ers are deep wounds, and often cause lockjaw. They should 
be carefully treated early, before it is too late. Splinters also 
make narrow deep wounds and are likely to cause lockjaw. 

Snakebites strike terror to the hearts of many persons, but 
this is not so much due to the actual danger from the bite as 
to man’s instinctive horror of snakes. As a matter of fact, the 
number of deaths occurring in Texas from snakebite is very 
small. In case one is bitten by a snake, unless he knows that 
the bite was inflicted by a harmless variety, it is well to pro¬ 
ceed as follows: If the wound is on a leg or an arm, as is 
likely, quickly throw a tourniquet or bandage that can be 
twisted tight around the limb between the wound and the 
heart. A handkerchief serves well for a bandage; out in the 
woods some twigs of tough plants will do. After bandaging, 


330 


The Human Body and Its Enemies. 


to prevent the blood from carrying the poison toward the 
heart, take a knife and sterilize the blade of it by flaming it 
with a match. Then make an incision over the wound of 
the snake’s fangs, cutting two cross marks each a quarter of 
an inch deep. Squeeze out as much blood as possible up to 
the amount of a wineglassful, but no more. 

You can always tell whether your treatment is effective or 
not, for, if ineffective the patient will become weak and pale 
in less than half an hour. This can be corrected by giving 
him a teaspoonful of spirits of camphor in half a teacupful 
of water. The tight bandage need not be kept on longer 
than thirty minutes in case no symptoms of weakness arise; 
but if they do, and the bandage is kept on longer, it should 
be removed for one minute every twenty minutes. 

A word of caution is here needed about the use of alcohol. 
Whiskey should ,not be used in case of snakebite. The med¬ 
icine to take along when on hunting and camping trips for 
snakebites is potassium permanganate. A strong solution of 
this in water is poured into the crossed incision described 
above. 

There are only a few poisonous snakes in Texas. The worst 
and most common are: the rattlesnake, which is familiar to 
most people the world over; the copperhead, which is a dull- 
mottled snake, having a blunt tail, and is found in dry up¬ 
land fields; and the cotton-mouth moccasin, which has a blunt 
tail and is white under the chin, and lives in streams and 
ponds. The prairie runner or coachwhip, the chicken snake 
and the garter snake are harmless. 

Fainting. —There are few accidents that excite the bystander 
more than fainting. When the fainting person falls, let him lie 
but see to it that he has plenty of fresh air. Fanning the 
patient is helpful, as is also the inhalation of lavender salts. 


Accidents and Emergencies. 


331 


The customary dash of cold water in the face is also good. 
Recovery from a fainting spell usually takes only a few min¬ 
utes. 

Burns. —Women and girls are especially in danger of getting 
burned because of their loose clothing, and also because of 
their duties in the house and around the fire. In 1911 there 
were 39 women accidentally burned to death in Texas. 

The most important point to keep in mind about burns is 
how to avoid them. Burning is a form of accident for which 
very little can be done before the physician arrives. It is 
well to keep unclean articles from touching the raw surfaces 
of the burn. It is not well to put water on large burns. The 
dead skin should be left in place until the doctor comes. 

Common Causes of Burns. —Burns are usually, though not 
always, the result of carelessness or ignorance with regard to 
the nature of coal-oil or kerosene. Never start a fire with 
kerosene oil! The oil is so easily touched off that the slight¬ 
est spark is sufficient to do so. Furthermore, when it once 
starts to burn in an open place like a stove it burns with such 
violence that burning oil. is thrown about. 

Smothering Flames. —Everj^one knows that when flames are 
fanned they burn more strongly. Therefore, when a person 
has caught fire he or she should be prevented from running 
wildly about. If no water is at hand in sufficient amounts, 
the flames may be smothered by throwing the burning person 
to the ground and piling on him or her rugs, blankets and 
similar articles that may be handy. 

Artificial respiration means making a person breathe when 
for any cause his natural breathing movements have stopped, 
as, for instance, when he has been shocked badly by elec¬ 
tricity, or when he has been under water and almost drowned. 
The best method of giving artificial respiration is a method 


332 


Accidents and Emergencies. 


which may be used by one person alone, and is illustrated by 
Figs. 258 and 259. The injured person is placed face down, 
and his head turned slightly to one side so as to keep the 
mouth out of the dirt. If possible, the head should be turned 

down hill. The person 
who gives the artificial 
respiration sits across the 
hips of the injured one, as 
shown in the picture, and 
places his hands on the 
other’s back and lower 
ribs. By alternately press¬ 
ing and releasing pressure 
with the hands, fifteen 
times to the minute, air is 
first pressed out and then 
drawn into the lungs. This 
method of artificial res¬ 
piration is especially good 
for the reason that the 
tongue does not fall back 
and stop up the throat, 
because the patient is ly¬ 
ing on his face. In the 
required, because the pa¬ 
tient was on his back and his tongue had to be held for¬ 
ward by a second person. The movements in artificial res¬ 
piration should never be forcible enough to injure the lungs, 
and as soon as the patient shows signs of gasping an at¬ 
tempt should be made to cause exhalation when he is try¬ 
ing to exhale. Of course, it would be unwise to make 
pressure on his chest when he were trying to inhale. 



Fig-. 258. First position in giving arti¬ 
ficial respiration. 



Fig. 259. Second position in giving ar¬ 
tificial respiration. 


older methods two persons were 






Accidents and Emergencies. 


333 


Important Points. 

1. If the injured one is breathing, and if he is not bleeding, 
there will not be any need for unreasonable haste. 

2. If he is bleeding very rapidly, anything clean pressed 
into and around the wound will stop the bleeding till you can 
do something further. 

3. Do not wash cuts with water unless the water has 
been boiled, and do not touch the cut with anything except a 
clean cloth. 

4. To avoid burns, do not take a large vessel full of oil near 
a stove; do not pour oil into a warm stove; and do not try 
to fill a lamp while it is lighted. 

5. To put out clothing that has caught on fire, throw the 
burning person to the ground and smother the flames with a 
wet or dry blanket or other cloth. 

6. Nail thrusts are dangerous and should be opened up 
thoroughly to let in air and prevent the growth of the tetanus 
or lockjaw germ. 


Questions. 

1. When is bleeding dangerous? 2. What is one sure way to stop 
bleeding? 3. Why is it unwise to wash a fresh cut? 4. Give two 
common causes of burns. 5. What accidents are likely to produce 
lockjaw? 6. Out on a ranch, what would you do if a friend were 
bitten by a large rattlesnake? 7. Would you prop up a person that 
has fainted or let him lie horizontally? 8. How do you give arti¬ 
ficial respiration? 


APPENDIX A. 


Sanitary and Unsanitary Outhouses. 


In the State of Texas there are a good many of that class of 
boys who believe in carrying into effect what they learn. Many of 
these boys are Boy Scouts. For these energetic and intelligent 
young men the following directions 
for making a sanitary privy, such as 
the one shown in Figs. 262 to 264 
are given: 

To begin with, we should recall 
that the three things necessary in 
closets are as follows: First, flies 
must he excluded absolutely; second, 
the closet must not overflow and 
drain into the well; third, the waste 
matter or night-soil, as it is called, 
must not flow out where it can be 
stepped on by barefooted boys, who 
might in this way get hookworm. 

Many boys will find that they can 
modify the water-closet which they 
already have so as to make it fulfill 
all these three requirements. For 
instance, a few yards of wire screen 

well placed will exclude flies with absolute certainty. A water¬ 
tight tub or other vessel can be placed underneath to catch the 
waste materials, and this tub must be emptied at intervals of a -week 
or two. It should be treated with some disinfectant each day or 
two: probably the coal tar disinfectants referred to in Chapter XVI 
are the best. 

For making an entirely new closet (and this would better be done 
where there is any doubt at all about the possibility of fixing up the 
old one) order the following materials: One piece 6x6 inches, 8 ft. 



Fig-. 262. When the lid is 
dropped, flies can not 
reach the receptacle or 
tub. 























Sanitary and Unsanitary Outhouses. 


335 


long. One piece 4x4 inches, 16 ft. long. 
Five pieces 2x4 inches, 16 ft. long. 
Three pieces 1x6, 16 ft. long. Two pieces 
1x9 inches, 9 ft. long. Three pieces 
1x10 inches, 7 ft. long. Fifteen pieces 
1x12 inches, 12 ft. long. Twelve pieces 
1-2x3 inches, 16 ft. long. Two pounds 
20-penny spikes. Six pounds 10-penny 
nails. Seven feet screen, 15 mesh, gal¬ 
vanized or copper, 12 inches wide. Four 
hinges six-inch strap. Two hinges six- 
inch “T” or three-inch huts for cover. 
One coil spring for front door. 

Having got this material ordered and 
delivered, cut the scantling as follows: 

A—Two pieces of lumber 4 feet long 
and 6 inches square at ends. 

B—One piece of lumber 3 feet 10 
inches long; 4 inches square at ends. 

C—Two pieces of lumber 3 feet 4 
inches long; 4 inches square at ends. 

D—Two pieces of lumber 7 feet 9 
inches long; 2 by 4 inches at ends. 

E—Two pieces of lumber 6 feet 7 inches long; 2 by 4 inches at 
ends. 

F—Two pieces of lumber 6 feet 3 inches long; 2 by 4 inches at 
ends. 

G—Two pieces of lumber 5 feet long; 2 by 4 inches at ends. 

H—One piece of lumber 3 feet 10 inches long; 2 by 4 inches at 
ends. 

I—Two pieces of lumber 3 feet 4 inches long; 2x4 inches at ends. 

J—Two pieces of lumber 3 inches long; 2 by 4 inches at ends. 

K—Two pieces of lumber 4 feet 7 inches long; 6 inches wide 
by 1 inch thick. The ends of K should be trimmed after being 
nailed in place. 



Figr. 263. Notice the screened 
windows or ventilators, 
and the trap-door on the 
seat. 


























336 


Sanitary and Unsanitary Outhouses. 


L—Two pieces of lumber 4 feet long, 

6 inches wide and 1 inch thick. 

Having got the lumber sawn into the 
right sizes, put it together as follows, 
referring to Fig. 264 as a model: 

First lay down the sills marked A 
and join them with the joist marked 
B; then nail in position the two joists 
marked C, with their ends 3 inches from 
the outer edge of A; raise the corner 
posts (D and F), spiking them at bot¬ 
tom to A and C, and joining them with 
L, I, G, and K; raise door posts E, 
fastening them at J, and then spike I, 
in position; H is fastened to K. 

After the frame is erected, the 
sides, ,floor, roof, seat, windows and 
doors can be built as shown in Figs. 

262 and 263. These pictures and di¬ 
rections are borrowed from Public 
Health Bulletin 37, written by Dr. C. W. Stiles and issued by the 
U. S. Marine Hospital Service. The bulletin may be had by writing 
to the service at Washington, D. C. Somewhat fuller instructions 
will be found in the bulletin than in this chapter. 



Fig:. 264. This shows how 
to erect the frame for a 
sanitary closet; see in¬ 
structions on this pag;e 
and the page preceding:. 

























APPENDIX B. 


Abstract of the Sanitary Code for Texas. 


[Note.—The Sanitary Code for Texas is important; it not only has a 
bearing- on the everyday life of each citizen in that it must be obeyed, 
but it also has great educational value, for it expresses the judgment 
of Texas Sanitarians and Legislators, as to the wisest method of com¬ 
batting preventable disease. There are many valuable rules in the Sani¬ 
tary Code which are not familiar to the citizens; some of these rules 
need to be invoked in time of epidemic, but others should be enforced 
every day to protect the public against such common dangers as tubercu¬ 
losis and typhoid fever, which in Texas, as elsewhere, are prevalent at 
all times. Again, some of the rules of the Code relate to schools. These 
have been printed in black-faced type, and will be of service to teachers 
and trustees.] 

Rule 1. Any physician in Texas who is called in to treat a per¬ 
son sick with any contagious disease is required to notify immedi¬ 
ately the local health authority. 

Rule 2. By “local health authority” is meant the city or county 
health officer or the local board of health. 

Rule 3. The following are considered as contagious diseases: 
Asiatic cholera, bubonic plague, typhus fever, yellow fever, leprosy, 
smallpox, scarlet fever (scarlatina), diphtheria (membranous 
croup), epidemic cerebro-spinal meningitis, dengue, typhoid fever, 
epidemic dysentery, trachoma, tuberculosis, and anthrax. 

Rule 4. The local health officer is required to keep a record of 
all contagious diseases reported to him, and to make a monthly* 
report of these cases to the State Board of Health. The records 
of tuberculosis are to be kept private. 

Rule 5. School trustees and health authorities are required to 
regulate their quarantine in a certain way, as follows: 

a. Absolute quarantine contemplates that no persons shall en¬ 
ter or leave the premises, guards being used to enforce this rule 
if necessary; the premises shall be placarded; no articles shall be 
allowed to pass out of the premises; food shall be furnished by 
the proper authorities under proper restrictions. 

b. Modified quarantine contemplates that the same restrictions 
shall apply as in absolute quarantine, except that certain mem¬ 
bers of the family can enter and leave the premises if they takt, 
precautions; while the sick person is required to be isolated in a 
certain part of the premises. 


338 


The Human Body and Its Enemies. 


c. Absolute isolation includes certain special measures of tech¬ 
nical interest. 

d. Modified isolation includes confinement of the patient and 
attendant in certain rooms, while the other members of the house¬ 
hold are allowed to enter and leave as they please. 

e. Special isolation includes prohibiting the patient from attend¬ 
ing any public assemblage, providing separate sleeping apartments, 
and eating utensils, towels, and napkins for the patient. 

f. Complete disinfection includes the disinfection during illness 
under direction of the physician of patient’s body, of all excretions 
or discharges, of all clothing and utensils used by patient; after ill¬ 
ness is over, the disinfection of walls, woodwork, furniture, bed¬ 
ding, etc. 

g. Partial disinfection includes disinfection of discharges or 
excretions of patients and their clothing and the room occupied by 
patient during illness. 

Rule 6. All disinfection required by these rules shall be done 
according to the method recommended by the Texas State Board 
of Health. 

Rule 7. When he receives information to the effect that a con¬ 
tagious disease exists in his territory, the local health officer is 
required to placard the house with a flag or a card of a certain 
size and bearing the inscription “Contagious Disease.” 

Rule 8. After a house is placarded, and placed under quaran¬ 
tine, no person except those authorized to do so by the local health 
authority is allowed to enter or leave the premises or carry away 
from the premises any article by which the disease might be spread. 
This rule holds until the premises shall have been disinfected and 
released from quarantine. 

Rule 9. When any person is exposed to a contagious disease, 
it is his duty to follow the instructions of the health officer, in 
order to avoid the spread of the disease. 

Rule 10. No person affected with any contagious or quarantina- 
ble disease shall be allowed to ride in any public conveyance, or 
to be present in any public assemblage, or to travel any public 
thoroughfare. 

Rule 11. It is unlawful for any person to remove or destroy the 
quarantine placard, and if it is removed, the owner of the premises 


Sanitary Code for Texas. 


339 


shall report this fact to the local health authority within twenty- 
four hours. 

Rule 12. The following diseases are not only quarantinable, but 
are pestilential, and persons suffering from any of them are to 
be kept in absolute isolation, and the premises are to be absolutely 
quarantined as described in Rule 5, and complete disinfection 
must be performed after the termination of the illness: Asiatic 
cholera, plague, typhus fever, yellow fever. 

Rule 13. The following diseases are dangerous contagious dis¬ 
eases, and persons suffering from any of them are to be placed in 
modified isolation, under modified quarantine, and complete disin¬ 
fection must be performed after the termination of the illness: 
leprosy, smallpox, scarlet fever (scarlatina), diphtheria (membra- 
bous croup) and dengue. 

Rule 14. The following diseases are to be treated by special 
isolation and partial disinfection: typhoid fever, cerebro-spinal men¬ 
ingitis, epidemic dysentery, trachoma, tuberculosis, and anthrax. 

Rule 15. The following diseases are quarantinable for school 
purposes, and persons suffering from these diseases are barred from 
school for twenty-one days: Persons suffering from measles, whoop¬ 
ing-cough, Geiunan measles (rotheln) and chicken-pox shall be re¬ 
quired to he barred from school for twenty-one days (at the discre¬ 
tion of the local health officer) from date of onset of the disease, 
with such additional time as may be deemed necessary, and may 
he readmitted on a certificate by him attesting to their recovery 
and non-infectiousness. 

Rule 16. Minor diseases are to be excluded during illness. 
Those actually suffering from tonsillitis, itch (scabies), impetigo 
contagiosa, and favus shall he excluded from school during such 
illness and be readmitted on the certificate of the attending physi¬ 
cian attesting to their recovery and non-infectiousness. 

Rule 17. Additional precautionary measures may be instituted 
at the discretion of the local health authority. 

Rule 18. When the local health officer hears of the existence 
of any contagious disease within the territory over which he has 
jurisdiction, it is his duty to investigate and if necessary declare 
a quarantine. 

Rule 19. The local health officer is required to see that all quar¬ 
antine in his territory is properly enforced, and that disinfection. 


340 


The Human Body and Its Enemies. 


when required by law, is properly done. Persons exposed to small¬ 
pox, if unvaccinated, are required to be held for eighteen days from 
date of last exposure. 

Rule 20. No person shall offer for rent any building in which a 
case of any quarantinable disease has occurred without previously 
having the building disinfected. This refers especially to houses 
which have been occupied by consumptives. 

Rule 21. If disinfection is not performed as required, the house 
in which the contagious disease has occurred shall be placarded 
by the local health officer. 

Rule 22. Nursese and midwives are required to report within 
twelve hours the presence of sore eyes or inflamed lids in the newly- 
born; this report is made to the local health officer or to any rep¬ 
utable physician. 

Rule 23. When any quarantinable disease occurs, it shall be 
the duty of the householder in charge of the premises to report 
the presence of the disease to the local health officer. In the pres¬ 
ence of a quarantinable disease, before quarantine is established, it 
is unlawful for any person to move out of the infected house, or 
to remove any articles from the house. 

Rule 24. No person suffering with any reportable disease, or 
who resides in a house in which there exists a case of smallpox, 
scarlet fever, diphtheria, or typhoid fever, shall work or be per¬ 
mitted in or about any dairy or any establishment for the manu¬ 
facture of food products, until the local health authority has given 
such a person a written certificate to the effect that no danger to 
the public will result from his or her employment or presence in 
such establishment. 

Rule 25. When he is notified of the presence of smallpox or 
other quarantinable disease, the local health officer shall send im¬ 
mediately to the physician, or with his approval, to the patient, 
printed matter published by the State Board of Health relating to 
such cases. 

Rule 26. Persons suffering from trachoma (granulated lids, con¬ 
tagious catarrhal conjunctivitis) are to be excluded from the schools 
unless they are under the strict supervision of a physician and 
hold a certificate from him to the effect that active inflammation 
has subsided; and this certificate must also be signed by the local 
health officer. 


Sanitary Code for Texas. 


341 


Kule 27. When any person suffering from smallpox, scarlet 
fever, or diphtheria is found to have been in a schoolroom, the 
school must be closed uutil the building has been properly disin¬ 
fected under the supervision of the local health officer. 

Rule 28. In the event that the disease causing the closing of 
school shall have been smallpox, the school must remain closed 
for eighteen days, unless the trustees require the vaccination of all 
unvaccinated pupils and teachers. In the latter case, the school 
may be reopened at once after disinfection. 

Rule 29. The local health authority shall notify the superin¬ 
tendent or principal of any school of the locations of quarantinable 
diseases, and if the superintendent or principal finds any attendants 
in such schools who live in said houses, he shall deny them admis¬ 
sion to the said schools, only admitting them again upon the pre¬ 
sentation of a certificate from the attending physician, countersigned 
by the local health authority, that there is no danger from con¬ 
tagion. 

Rule 30. No superintendent, principal, or teacher of any school, 
and no parent, master or guardian of any child or minor, having 
the power and authority to prevent, shall permit any such child 
or minor, having any quarantinable disease, or any child residing 
in any house in which any such disease exists or has recently ex¬ 
isted, to attend any public, private, parochial, church or Sunday 
school until the requirements of these rules have been complied 
with. 

Rule 31. In cities and incorporated towns, the city health au¬ 
thorities shall assume control of quarantine, isolation, and disin¬ 
fection; in districts outside of cities and towns, the county health 
officer shall assume control. 

Rule 32. Cities, counties, and towns have the privilege of de¬ 
claring quarantines independently of the State Health Authorities, 
so long as the additional quarantine is consistent with and sub¬ 
ordinate to the quarantines established by the Governor and State 
Board of Health. In case any local health authorities declare a 
quarantine, they are required to notify the State Board of Health. 

Rule 33. All health authorities have the privilege of passing 
through quarantine lines provided they announce that they are ac¬ 
quainted with the disease they are visiting and will take precau¬ 
tions to prevent its spread. 


342 


The Human Body and Its Enemies. 


VITAL STATISTICS. 

Rule 34. Each birth occurring in Texas shall be reported by the 
physician, surgeon, or midwife, or in the absence of these, by the 
parent, to the city or county registrar. 

Rule 35. Undertakers shall report each death to the local reg¬ 
istrar, and the individual or firm selling the coffin is considered 
the undertaker. 

Rule 36. All births and deaths, except those occurring in a 
city or incorporated town, shall be reported to the clerk of the 
county court; in cities and incorporated towns, births and deaths 
are reported to the city registrar. 

Rule 37. Each city or incorporated town is a primary registra¬ 
tion district. The city health officer shall be the local registrar. 
Each local registrar shall appoint a deputy to serve during his ab¬ 
sence or disability, and both registrar and deputy are subject to 
the rules of this Code; provided, that in cities or towns where the 
secretary or other official is serving as local registrar, and where 
a burial or removal certificate is required before allowing any dead 
body to be buried within or removed from the city limits, such city 
secretary shall continue as the local registrar, but shall be sub¬ 
ject to the regulations of this code. No body must be removed 
from or interred in any local registration district until the local 
registrar has issued a burial or removal certificate, and such cer¬ 
tificate shall not be issued by the local registrar until he has re¬ 
ceived and filed the death certificate as described later; but a death 
or removal certificate issued in accordance with the law of the place 
the death occurred, whether in Texas or not, shall be sufficient au¬ 
thority for the local registrar to grant a burial permit; in this case, 
the local registrar shall write plainly across the face of the copy 
of the record which he sends in to the State Registrar the fact 
that the body was shipped in for burial. The city registrar is re¬ 
quired to record in a permanently bound book all births and deaths, 
with the statistical data required by law, and at the end of each 
month, the city registrar shall forward to the State Registrar a 
copy of each birth or death certificate filed with him during the 
month. 

Rule 38. All certificates of births and deaths shall be made ac¬ 
cording to the form prescribed by the State Board of Health. 


Sanitary Code for Texas. 


343 


Rule 39. For each dead body for which he provides a coffin, 
the undertaker shall fill out the death certificate, and shall turn 
the certificate over to the physician for the latter to give a signed 
statement as to the cause of death. The undertaker or physician 
shall then send the death certificate to the local registrar. 

Rule 40. It is the physician’s duty to be prompt in filling in 
the “medical particulars” of the death certificate. 

Rule 41. In rural districts, where no undertaker officiates, the 
last attending physician shall hand in the death report. 

Rule 42. Where a person dies without medical attendance, the 
coroner,, if one is called in, shall file the death report; if no coroner 
is called in, the householder on whose premises the death occurred 
shall report the death to the local health officer; the latter shall 
issue the death certificate, after holding an autopsy if necessary. 

Rule 43. If a death occurs in a hospital, certain statistical facts 
are required to be given by the superintendent of the hospital be¬ 
fore the undertaker sends in the report. 

Rule 44. If any physician, coroner, or superintendent of any 
hospital refuses to fill in the medical particulars on the death re¬ 
port, the undertaker shall report this fact to the State Registrar 
for prosecution. 

Rule 45. This relates to stillbirths, which shall be reported as 
both deaths and births. 

Rule 46. The county clerk in each county shall preserve a 
bound record of all data contained in death and birth reports, and 
shall report monthly to the State Registrar of Vital Statistics. 

Rule 47. Each sexton of a cemetery is required to file all burial 
permits received, and to send in a monthly report of all bodies 
interred to the State Registrar of Vital Statistics. 

Rule 48. The State Registrar is required to have printed all 
death and birth certificates, while the city and county governments 
are required to have printed the permanently bound book for pre¬ 
serving birth and death records. The State Registrar has author¬ 
ity to require additional information about any birth or death from 
any person in possession of the facts. 

Rule 49. The city and county registrars are required to fur¬ 
nish the birth and death certificate blanks to all persons using 
or requiring them. 

Rule 50. The city or county registrar shall examine certificates 


344 


The Human Body and Its Enemies. 


of birth and death to see that they are complete. He shall num¬ 
ber the births and deaths in separate series, commencing anew at 
the beginning of each year. 

DEPOTS, RAILWAY COACHES, AND SLEEPING CARS. 

Rule 51. No person known to be suffering from smallpox, diph¬ 
theria, measles, scarlet fever, or whooping cough shall be allowed 
to enter or ride in any railway coach or street car, and in case 
any such person is discovered in such car, it shall be the duty of 
the conductor to notify the nearest local health officer who shall 
remove and isolate the patient as required by law. 

Rule 52. All depots, railway coaches, interurban cars, and street 
cars must be properly ventilated and, in cold weather, heated. 

Rule 53. Cuspidors in adequate numbers must be provided in 
all depots and waiting rooms, as well as in railway coaches; these 
cuspidors must contain at least one-third pint each of some ap¬ 
proved disinfectant solution, and must be-cleaned out every twenty- 
four hours. 

Rule 54. Dry dusting and sweeping is prohibited at all times 
in waiting rooms of depots and railway stations, and in railway 
coaches, interrurban cars, and street cars. 

Rule 55. Railway day coaches shall be thoroughly cleaned ac¬ 
cording to the method prescribed by law at the end of each trip, 
or at least as often as once in forty-eight hours, when in use. 

Rule 56. Railway waiting rooms shall also be cleaned in a sani¬ 
tary manner once in each twenty-four hours. 

Rule 57. Parlor, buffet, and dining cars must be thoroughly 
cleaned at each terminal; food-boxes, refrigerators, closets, draw¬ 
ers, and cupboards must be cleansed, scalded, and disinfected with 
an approved disinfectant. 

Rule 58. Interurban and street cars must be washed with a 
hose and scrubbed thoroughly once every twenty-four hours, and 
must be fumigated immediately after any case of contagious dis¬ 
ease has been discovered therein. 

Rule 59. Sleeping cars must be cleansed thoroughly and dis¬ 
infected at least twice in each week, except that on certain lines 
designated by the President of the State Board of Health, one 
cleansing and one disinfection per week may suffice; these cars 


Sanitary Code for Texas. 


345 


must always be disinfected, however, immediately after any one 
suffering from any contagious or infectious disease is discovered 
therein. 

Rule 60. In each passenger car operated in Texas, a signed 
record must be kept showing the place and date of each disinfec¬ 
tion, the length of time devoted to such disinfection, and the name 
of the person doing the disinfecting. 

Rule 61. All depots, railway coaches, interurban cars, and sleep¬ 
ing cars must be provided with a water cooler for the use of 
patrons; these coolers must be kept sanitary, must be cleansed 
once in each twenty-four hours, and the ice used therein must 
be handled with tongs, and not dumped on floors, sidewalks, or car 
platforms. 

Rule 62. Expectorating or spitting on the floors, walls, or fur¬ 
niture of any depot, waiting room, platform, or any street car. 
railway coach, or interurban car is prohibited, and placards must 
be displayed calling the attention of the public to this fact. 

Rule 63. Brushing of teeth or expectorating in basins used for 
lavatory purposes is prohibited, and placards announcing this fact 
shall be hung in proper places. 

Rule 64. Sleeping car companies shall provide separate com¬ 
partments for their negro porters. 

Rule 65. Negro porters shall not sleep in sleeping car berths 
nor use bedding intended for white passengers. 

Rule 66. No waiting room* in any railway station or depot shall 
be floored in part or entirely with burlap or coca matting. 

Rule 67. All depots and railway stations shall be provided with 
water closets which shall be so constructed as to exclude flies; these 
water closets shall be kept in sanitary condition, and shall be 
cleaned, emptied, and disinfected at least once in each thirty days. 

Rule 68. The premises of all railway stations shall be thoroughly 
drained, so that no stagnant water shall collect thereon. 

Rule 69. All cisterns, fire-water barrels, or other water con¬ 
tainers upon the premises of any depot or railway station shall be 
screened with not less than 16-mesh wire gauze. 

NOTE: —The rules governing: the transportation of dead bodies are 
omitted. Threy are of technical interest and can be obtained frofn any 
railway or express agent. 


APPENDIX C. 


Poisoning. 


When a person has taken poison, there are certain general rules 
to follow, whether the nature of the poison be known or not. These 
general rules are given below, together with special reference to the 
commoner poisons. 

If the patient seems faint, let him lie down; then give him stim¬ 
ulants, such as a cup or two of strong coffee, a teaspoonful of aro¬ 
matic spirits of ammonia, a teaspoonful of Hoffman’s anodyne, or a 
drink of whiskey. 

If a patient seems sleepy, keep him awake by bathing his face 
with cold water and fanning him; but do not wear him out by 
walking him around. 

If the extremities are cold, warm them with hot water bottles or 
warm bricks or stove-eyes. 

To produce vomiting, a tablespoonful of mustard in a pint of 
warm water is immediately effective. Warm, salty water in large 
amounts is also good. The stomach tube is good in the hands 
of a physician or nurse. 

If an acid has been swallowed (carbolic acid is not here in¬ 
cluded) alkaline substances should be given, such as cooking soda, 
prepared chalk, whiting, magnesia, limewater. Follow with raw 
eggs or olive oil. « 

If a strong alkali has been taken, such a concentrated lye, acids 
like vinegar or lemon juice, should be given. Follow with raw eggs 
or olive oil. 

Carbolic acid poisoning must be treated within twenty minutes 
or death may result. The treatment is undiluted whiskey, or pure 
grain alcohol diluted half and half with water. If this is not at 
hand, epsom salts in the usual doses is almost as good. If the al¬ 
cohol is used, epsom salts should be used a little later 

Poisoning from rough on rats or other forms of arsenic should 
be treated by remedies to cause vomiting as described above. These 


Poisoning. 


347 


should be followed or accompanied by raw eggs or cooked starch 
paste. The druggists prepare a regular antidote to arsenic, which 



Fig-. 265. Medi¬ 
cines and poi¬ 
sons should be 
locked up out of 
the reach of 
children. 


should be given as soon as it can be obtained. 

Phosphorous poisoning should be treated 
by remedies to cause vomiting, and by stimu¬ 
lants and raw eggs. No oil should be given 
under any circumstances. 

Morphine, paregoric, laudanum and other 
forms of opium all act alike, and should be 
treated by remedies which cause vomiting, by 
tannic acid, one teaspoonful, or by potassium 
permanganate, five grains, repeated in ten 
minutes. In addition, the patient should be 
kept awake by strong coffee, cold water, and 
attempts at rousing. 

To avoid poisoning, the medicines and 
poisons should be kept out of the reach of 


children, and should never be given in the dark. When concen¬ 


trated lye is used in scrubbing the floor, the open can should never 


be left on the floor or in reach of children. 




INDEX 


Abdominal cavity, 125*. 

Absorption, 174-178, 175* 

Accidents, 326-333. 

Accommodation of the eye, 318*. 

Acid in gastric juice, 15, 167 (n). 

Adenoids, 190*, 335. 

Air, 187, 199; waves of, 306; 
fresh, 54, 259. 

Air passages, 189*. 

Air sacs, 189*, 193*, 195, 196*. 

Alcohol, Stimulants and Narcot¬ 
ics, 291-298. 

Alcohol, and the circulation, 222- 
223; and body heat, 236-237; 
and muscular strength, 258; 
how made, 291; percentage of, 
292; habit, 294*; and the ath¬ 
lete, 294-295 ; and business, 295. 

Alcohol, effects on the respira¬ 
tory system, 191, 293; on the 
stomach and liver, 292-293; on 
the kidneys, 227, 293; on the 
heart, 222, 293 ; on bones and 
muscles, 249, 294; on the 

nerves, 294. 

Alimentary canal, 163-168*. 

Amylopsin, 155. 

Anatomy, defined, 125. 

Animals, food of, 137. 

Anopheles, mosquito, 61*, 62*, 
93, 95*; and malaria, 65, 

Antitoxins, 183*; and serums, 20- 
21; and diphtheria, 56; and 
meningitis, 59. 

Anvil, 306*, 307. 


Aorta, 209*, 210. 

Appendicitis, 163 (n). 

Appendix, vermiform, 156*, 163. 

Aqueous humor, 313*. 

Arteries, 179, 208*, 209*, 211*, 
213*; hemorrhage of, 326. 

Artificial respiration, 331-332. 

Assimilation, 179-184, 180*. 

Asthma, 196. 

Astigmatism, 321. 

Auditory canal, 306*. 

Auricles, 209*, 210*. 

Bacteria, or germs, 4-9; causing 
decay of the teeth, 160; in 
foods, 144*; in milk, 146; kill¬ 
ed by cooking, 145; food of, 5, 
183; toxins of, 5, 183. 

Bathing, 239-340. 

Bile, 167; duct, 167*. 

Bladder, gall, 167*; of kidneys, 
227. 

Bleeding, 326-327. 

Blood, as a carrier, 179, 205*\ 
206, 217; circulation of, 205- 
215; in frog, 207*; description 
of, 216-219; clotting, 218*, 219*. 

Blood vessels, 179, 208*, 209*, 
212*, 213*. 

Body, the human, as a machine, 
1-3; a house of many parts, 
124-129 ; cavities of, 125* ; heat 
of, 234-242; effects of alcohol 
on, 291-296. 

Bone, cells of, 248* ; tissue, 248* ; 
composition of, 249*. 



Index. 


349 


Bones, and joints, 243-253; uses 
of, 244-246; kinds of, 244-245; 
effect of alcohol on, 249, 294; 
broken, 327*. 

Bookkeeping on health and dis¬ 
ease, 119-124, 342. 

Brain, 267-273. 

Breathing, 193*, 194. 

Bronchial tubes, 189*. 

Bubonic plague, 80-82. 

Burns, 331. 

Buying food, 141. 

Canned foods, 144*. 

Capillaries, 179, 180*, 208*; and 
gland cells, 170*, 171*; in villi, 
175*, 176*; near cells of body, 
180*; about air sacs, 196*; 
near kidney cells, 226*; in 
skin, 228*; about coil of sweat 
glands, 231*. 

Carbohydrates, 134-135; use of, 
137. 

Carbon, 131. 

Carbon dioxid, 185, 186*, 255; 
experiment, 188*. 

Carroll, Dr., and yellow fever, 10. 

Cartilage, 191, 243. 

Cells, human body composed of, 
128; kinds of, 127* 170*, 175*, 
216*, 217*, 248*, 249, 258* 

265*; ciliated, 192*; absorp¬ 
tive, 175* ; growth and division 
of, 181* 180*; 181, 183; food 
of, 180*; fatigue of, 260. 

Cerebellum, 271, 272*. 

Cerebro-spinal meningitis, 58, 84, 
268(n). 

Cerebrum, 270-271*. 

Chemical digestion, 153, 157. 


Chemical disinfectants, 113. 

Chest, or thorax, 244*; cavity of, 
125; used in breathing, 194*. 

Cholera, 68. 

Choroid coat of the eye, 313*, 
314. 

Cigarettes. See Tobacco. 

Cilia, 192*, 193*. 

Ciliated cells, 193*. 

Ciliary muscles, 313*, 318*. 

Ciliary process, 313*, 318*. 

Circulation of the blood, 179, 205- 
215. 

Clavicle, or collar bone, 244*. 

Closets, sanitary and unsanitary, 
236-239. 

Clothing, 237-239; for Texas cli¬ 
mate, 238; tight, 250*; how to 
disinfect, 37*. 

Clotting of blood, 218*. 

Cochlea, 308*, 309*. 

Coffee and tea, 296. 

Colds, 236; germs of, 52-55. 

Connective tissue, 126, 127*. 

Consumption or tuberculosis, 42- 
51; prevalence, 42 ; cause, 43 ; 
how spread, 43-48; curable, 
48; how prevented, 49-51. 

Contraction; of muscles, 254-255; 
of heart, 210*. 

Convolutions of the brain, 269*. 

Cooking, 144-145. 

Cooperation of organs, 263-264. 

Cornea, 313*, 314, 317. 

Corpuscles of the blood, 216*, 
217*, 218*. 

Cost of food, 141. 

Coughing, and tuberculosis, 46. 

Cowpox, 17, 18., 



350 


Index. 


Cows and tuberculosis, 146*; 
milking, 147*. 

Cranial nerves, 268*. 

Culex, mosquito, 92*, 95*; and 
dengue, 65, 66. 

Cuts and wounds, 327. 

Dairy and Food Commissioner, 
146. 

Dengue, 65, 66. 

Dermis, 228*, 229. 

Diaphragm, 124*, 125; used in 
breathing, 194*, 195. 

Digestion, 150-172 ; chemical, 153, 
155, 157 ; mechanical, 158; or¬ 
gans of, 156-173 ; in the mouth, 
156-161; juices, 167; experi¬ 
ments in, 150, 154. 

Diphtheria, 56-58; antitoxin. 120, 
56-57; carriers of, 84. 

Disease carriers, 33, 83-85. 

Disease germs, 2, 4-9 ; and lymph 
nodes, 220; . in water, 100-110; 
in milk, 146, 33. 

Diseases, communicable, 10-14; 
our protection against, 15-28. 

Disinfectants, 111-118; in ty¬ 
phoid fever, 36-39. 

Dorsal cavity, 125*. 

Drinking* cups, 57; sanitary, how 
to make, 106. 

Drinking fountains, 107. 

Drowning, apparent, 331. 

Dry sweeping, 44 ; prohibited by 
law, 344. 

Ducts, of glands, 171; thoracic, 
177*, 220. 

Dust, and tuberculosis, 44-46. 

Ear, 306-310; care of, 307. 


Ear drum or tympanum, 306*, 
307. 

Eating habits, 141. 

End cells of sense organs, 300*, 
302, 303* 304*, 308*, 313* 315. 

Energy, foods for, 131. 

Enzymes, 153, 155. 

Epidermis, 228*. 

Epiglottis, 189*, 191, 193*. 

Epithelial tissue, 127*, 128; of 
glands, 169, 170*; ciliated, 

192*. 

Esophagus, or gullet, 124*, 125*, 
156, 163, 164. 

Eustachian tube, 306*, 307, 309*. 

Excretion, 224-233. 

Exercise, 259*, 260*. 

Expiration, 186. 

Eyes, 311-325; protection of, 311- 
313; structure and function of, 
313-319; care of, 321-325; sore, 
323. 

Fainting, 330. 

Far-sightedness, 320*. 

Fat, 136; a fuel food,. 138; cells, 
182*; tissue, 127. 

Fatigue, 260, 289. 

Feather duster, 45-46. 

Feet, hygiene of, 250*, 251*. 

Fibers, 127. See Nerve , muscle , 
etc. 

Flagging a hotfse, 69*. 

Fleas and plague, 81, 97*. 

Flies, life history of, 85-89*; as 
disease carriers, 30, 31, 35, 87- 
88 ; how to destroy, 89. 

Focusing, 316-318*. 

Follicle, of hair, 228*, 229. 



Index. 


351 


Foods, uses of, 131; kinds of, 
134-139 ; experiments with, 135- 
137; cost of, 141; pure, 140- 
150 ; buying, 141; canned, 144 ; 
vegetables and cooking, 145*; 
of cells, 180*; of muscles, 258. 

Foot. See Feet. 

Fumigation, 115, 116*. 

Gall bladder, 167*. 

Ganglia, 269, 279*. 

Gangrene, 327. 

Gastric glands, 165*, 166, 167, 
171*. 

Gastric juice, 154, 155; as a dis¬ 
infectant, 15. 

General sensations, 299. 

Germ carriers. See Disease Car¬ 
riers. 

Germ diseases. See Disease 
Germs. 

Glands, salivary, 157*; parotid, 
157*; sublingual, 157*; sub- 
maxillary, 157*; intestinal, 
165*, 166; gastric, 165*, 166; 
cells of, 169, 170; structure of, 
169-173*; sweat, 170*, 228* 

230-231, 235; oil, of skin, 228* 
230; tear, 312*; oil, of eye¬ 
lids, 34 2. 

Gnats, and sore eyes, 323. 

Government, duty of, 50. 

Governor to declare quarantine, 
341. 

Grape sugar, 135. 

Gray matter, of brain and 
spinal cord,- 269*. 

Grip, germs of, 52-54. 

Ground itch, 76. 

Gullet. See Esophagus. 


Gymnastic exercise, 259. 

Habits, 281-282; eating, 141. 

Hair, 228*, 229-230. 

Hand, and cleanliness, 54. 

Health, 119. 

Health officers, reports of, 342. 

Hearing, 306-310. 

Heart, location of, 124*, 125*, 
209*; action of, 210*; struc¬ 
ture of, 209*; valves of, 211*, 
213*; hygiene of, 221; and al¬ 
cohol, 22, 293; and tobacco, 
222 . 

Heat, of the body, 132; and bac¬ 
teria, 145; regulation of, in 
body, 234-242; as a disinfect¬ 
ant, 37*, 113*. 

Heating and ventilation, 200- 
203*. 

Hemoglobin, 217. 

Hemorrhage, 327. 

Heredity and tuberculosis, 47. 

Hookworms, 75-79, 76*; how 

spread, 77*. 

Hydrophobia, vaccination 
against, 19. 

Hygiene, 125; of food, 140-149; 
of the teeth, 160-161; of the 
breathing organs, 195-197; of 
ventilation, 199-204; of the 
circulation, 221-223; of the 
kidneys, 227; of the skin, 230- 
242; of joints, 248; of bones, 
249-252 ; of muscles, 258-261; 
of the nervous s ystem, 284- 
290; of the ear, 307; of the 
eye, 319-324. 

Immunity, 17-28; artificial. 17- 
24; natural, 16, 25-27. 




352 


Index. 


Impulses, nerve, 264, 275, 278*, 
300. 

Incubation period of diseases, 68. 

Influenza. See Grip. 

Insects, as carriers of disease, 
86-99; house flies, 30, 31, 35, 
86-91; tse-tse fly, 91; mosqui¬ 
toes, 61-66, 91-97; fleas, 81, 
97 ; lice, 97 ; ticks, 97-98 ; gnats, 
323. 

Inspiration, 186. 

Intestinal glands. See Glands. 

Intestinal juice, 154, 155. 

Intestine, 156*, 165*, 166, 174- 
176; worms in, 75-78. 

Involuntary muscles, 256. 

Iris, 313*, 314. 

Isolation. See Quarantine. 

Joints, 246-248; structure of, 
247*; hygiene of, 248*. 

Juices, digestive, 153, 155. 

Kidneys, 225, 226*. 

Knee cap (patella), 244. 

Koch, Dr. Robert, 84. 

Lacteals, 176*, 177* 

Larynx, 189*, 190. 

Lazear, Dr., and yellow fever, 10. 

Lens, of the eye, 313*, 317*, 318* 
320. 

Leprosy, 70. 

Lice, and typhus or jail fever, 
70, 97. 

Ligaments, 243, 247*; of the lens 
of the eye, 318*. 

Light, as a disinfectant, 111; 
and sight, 311; refraction of, 
315*, 316*; in reading, 321-322. 

Liver. See Glands; and portal 


vein, 176, 177*; and alcohol, 
293. 

Lockjaw (tetanus), 328; anti¬ 
toxin, 21-32. 

Lunches, school, 141. 

Lungs, 192-197, 193*; air sacs of, 
189*, 193*, 195, 196*. 

Lymph, 177*, 180*, 219-222; 

node, 220, 222*. 

Lymphatics, .220, 221*. 

Malaria, 61-65; discovery of 
cause, 62; prevention, 63. 

Measles, and quarantine, 72. 

Meat poisoning, 144. 

Mechanical digestion, 152. 

Medulla, 271, 272*. 

Membranes, mucous, 164, 165*, 
175, 176*; synovial, 246; as 
coverings of brain and spinal 
cord, 268, 276*. 

Meninges, 268 (n) ; diseases of, 
58-60. 

Meningitis, 58-60; how to avoid, 
59; carriers of, 84. 

Microscope, the, 4, 128. 

Milk, as a food, 146; oil globules 
in, 154*; bacteria in, 47, 146; 
care of, 147-148; curdled by 
rennin, 155. 

Milking, 147*. 

Mind, the brain the organ of, 
270. 

Minerals, in food, 138; in bone, 
249*. 

Mixed diet, 140. 

Mosquitoes and malaria, 61-65; 
and yellow fever, 65 ; and den¬ 
gue, 65-66; life history of, 92- 
OS ; how to destroy, 96-97. 



Index. 


353 


Motor nerves, 276. 

Mouth, digestion in, 156-161. 

Mucous membrane, 164, 165*, 

175*, 176*; ciliated, 193*. 

Muscle, fibers or cells, 127*, 126, 
256*, 257*. 

Muscles, the, 254-262, 254*; tis¬ 
sue, 126; uses of, 254-255; 
kinds of, 256-257; of arm, 255; 
structure, 257*; of alimentary 
tract, 164, 165*; of eye, -311*, 
313; ciliary, 318*. 

Nails, the, 230*. 

Nasal, passage, 124*, 189*, 190*, 
303* 

Near-sightedness, 318, 319*. 

Nerves, tissue, 126; cells or fi¬ 
bers, 264*, 265; function of, 
265; cranial, 268*; spinal, 
275*; of cerebrum, 270*; mo¬ 
tor and sensory, 276; of touch, 
300*; of taste, 302, 303*; of 
smell, 304*; of hearing, 308; 
of sight, 313*, 314. 

Nervous system, 263-325, 264*; 
central, 266, 267; periferal, 

266, 267; and germ diseases, 
285*; care of, 284-290. 

Nodes, lymph, 220, 222*. 

Nucleus, of cells, 128. 

Olfactory nerve (nerve of 
smell), 304*. 

Opiates, 297. 

Optic nerve (nerve of sight), 
313*, 314. 

Osmosis, 177*. 

Overwork, 286*. 

Outdoor sleeping, 49, 203. 


Outhouses, 337-339; unsanitary, 
77. 

Oxidation of foods, 131, 138, 185. 

Oxygen and food, 131; need of, 
138; experiments, 187*; in air, 
187; carried by red blood cor¬ 
puscles, 217. 

Palate, 156, 157*, 190. 

Pancreas. S eeGlands. 

Papillae, of tongue, 302*, 303*. 

Parasites. See Hookworm , Tape¬ 
worm, Bacteria, etc. 

Pasteur, and vaccination, 18. 

Patella, or knee cap, 244*. 

Pellagra, 75. 

Pelvis, 24^ 

Pencils, and disease, 57. 

Pepsin, 155. 

Peptones, 154. 

Pericardium, 208. 

Periosteum, 248*, 249. 

Peristalsis, 164*. 

Peritoneum, 165*, 166. 

Pharynx or throat, 156, 189*. 

Physiology defined, 125. 

Pimples, 232. 

Plague, bubonic, 80-82. 

Play, 259, 260*; playgrounds, 

260. 

Plexuses, 279*. 

Pleurisy, 193. 

Pneumonia, 196; and alcohol, 
53; germs of, 53. 

.Poisons, 346; in meat, 144; in 
cells, 260; in bad air of rooms, 
199-200. 

Pollution, of soils, 77; of water, 
32, 100-109. 

Portal vein, 177*, 212. 



354 


Index. 


Protection against disease, 15- 
28. 

Proteids, 136; a building- food, 
138. 

Protoplasm, 180*. 

Ptyalinc, 153, 155. 

Public drinking- cup, 57; towel, 
57*. 

Pulmonary artery, and veins, 
209, 210*. 

Pupil of the eye, 313*, 314*. 

Pure food, 141-150. 

Pylorus, 164, 165*. 

Quarantine, 67-74; state law con¬ 
cerning, 337. 

Quinine, 112. 

Rabies, or hydrophobia, 19. 

Rats and plague, 81. 

Reflex action, 277, 278* 280; or¬ 
gans of, 272-277. 

Renal artery and vein, 225, 226*. 

Reportable diseases, 68-69. 

Reporting diseases. See Vital 
Statistics. 

Resistance to germs of disease, 
16, 52. 

Respiration, 185-198*, 196*; or¬ 
gans of, 189-198; experiments, 
187; artificial, 331, 332*. 

Rest, 261, 288; of eyes, 321. 

Retina, 313*, 315, 316. 

Rickets, Dr., -and typhus fever, 

10 . 

Ribs, used in breathing, 194*. . 

River water, 104. 

Ross, Dr. Ronald, and malaria, 
62. 

Salivary glands. See Glands. 

Scapula, or shoulder blade, 244*. 


Sanitary code for Texas, 337. 

Scarlet fever, and quarantine, 71. 

Sclerotic coat of the eye, 313*, 
314. 

School desks, 251*. 

School rooms, ventilation of, 
202, 203*; lighting of, 322. 

Schools, quarantine, 71, 341. 

Sclerotic coat of the eye, 313*, 
314. 

Screens, 63*, 64, 97. 

Sections of organs, 162*. 

Semicircular canals, 306*, 309*. 

Sensations, 271, 300; general, 

299. 

Senses, the special, 299-325. 

Sensory nerves, 276. 

Serum, 220*. See also Anti¬ 
toxins. 

Shoulder blade, of scapula, 244*. 

Sight, 311-325; defects of, 319- 
321. 

Skeleton, the, 243-253, 244*. See 
also Bones. 

Skin, the, 228-233, 228*; and 

regulation of body heat, 234- 
242; a protection against 
germs, 15. 

Skull, the, 244*, 268. 

Sleep, 287; outdoor, 203. 

Sleeping sickness, 91. 

Smallpox, 17, 22-25, 23*; quar¬ 
antine, 71. 

Smell, 200, 303*, 304*. 

Snakebites, 229-230. 

Soap and water, 112. 

Soil pollution, and hookworm, 77. 

Sore eyes, 323. 

Spectacles, 322. 



Index. 


355 


Spinal column, 124*, 125, 268, 
244*. 

Spinal cord, 274-279 ; description 
of, 274, 275; functions of, 275, 
276; nerves of, 275*, 277. 

Spitting-, 50; prohibited where, 
345. 

Spleen, 125*, and blood cor¬ 
puscles, 216; a lymph node, 
320. 

Squirrels, and plague, 80*. 

Starch. 135. 

State Bacteriologist, 114. 

State Board of Health, 68, 114, 
115, 337. 

State Registrar of Vital Statis¬ 
tics, 121, 341. 

Steapsin, 155. 

Stegomyia, mosquito, 92*; and 
yellow fever, 65. 

Sternum, or breast bone, 244*. 

Stimuli, nerve, 300. 

Stomach, bacteria in, 15; diges¬ 
tion in, 154, 156*, 167; descrip¬ 
tion of, 163, 165*; glands of, 
166. 

Sugar, 135, 136. 

Sweat glands. See Glands. 

Sympathetic nervous system, 
279. 

Tapeworm, 78, 144*, 145. 

Taste, 202, 203*. 

Tea and coffee, 296. 

Teachers, duties of, when com¬ 
municable diseases occurs in 
school, 337, 339. 

Teeth, 158-161; structure of, 160, 
161*; care of, 160. 


Temperature of the body. See 
Heat. 

Tendons, 243, 257*. 

Tetanus, or lockjaw, 328*; anti¬ 
toxin, 21-22. 

Texas, vaccination in, 24; ty¬ 
phoid fever, 29, 36, 38, 40, 107; 
consumption, 44, 48; diphthe¬ 
ria, 56 ; malaria, 62 ; yellow fe¬ 
ver, 65; dengue, 66; quaran¬ 
tine, 68, 73, 337-341; Sanitary 
Code, 69, 337-345; typhus fever, 
70, 97 ; leprosy, 71; measles, 72 ; 
pellagra, 75 ; hookworm, 75-79 ; 
plague, 82, 97; mosquitoes, 91- 
92; screens, 97; drinking wa¬ 
ter, 102, 104, 105, 107; disin¬ 
fectants, 114-116; vital statis¬ 
tics, 120-124, 242-244; canned 
foods, 144; tuberculosis in cat¬ 
tle, 146 ; outdoor sleeping, 203 ; 
ventilation of schoolhouses, 
203 ; clothing, 238 ; snake bites, 
329. 

Thoracic cavity, 125*. 

Thorax, or chest, 244*, 245; used 
in breathing, 194*. 

Throat. See Pharynx. 

Thymol, and worms, 78. 

Ticks, as disease carriers, 98. 

Tissues, 126. 

Tobacco, cigarettes and the 
lungs, 196, 197; and the 

muscles, 258; and the develop¬ 
ment of bones, 249; and the 
heart, 222, 223. 

Tongue, 157*. 

Tonsils, 157*. 

Touch, 299-301; buds, 228*, 300*. 



356 


Index. 


Toxins, 15, 183*. 

Trachea, or windpipe, 189*, 192, 
193*. 

Trachoma, 323. 

Trichina, 145*. 

Trypsin, 155. 

Tse-tse fly and sleeping sickness, 
91. 

Trustees, duties of, 337, 339. 

Trypsin, 155. 

Tuberculosis, or consumption, 
42-51. 

Tympanum, or ear drum, 306*, 
307, 309*. 

Typhoid carriers, 33, 83. 

Typhoid fever, vaccination 
against, 16, 19-20; how scat¬ 
tered, 29-33; how prevented, 
34-39; and water, 107-108. 

Typhus fever, a reportable dis¬ 
ease, 70; spread by lice, 70, 97. 

Ureter, 124*, 226*. 

Uric wastes, 225, 180*. 

Uvula, 156, 157*. 

Vaccination, discovery of, 17; 
against typhoid fever, 19; 
against smallpox, 22-25; re¬ 
quired by law, 341. 

Vaccines, 19. 

Valves of the heart, 211*, 213*; 
pylorus, 164, 165*. 


Veins, 179, 208* 213; portal, 

212 . 

Ventilation, 199-204; of bath¬ 
room, 241. 

Ventral cavity, 125*. 

Ventricles of heart, 209*, 210*. 

Vertebrae, 124*, 244*, 245*. 

Villi, 165*, 166, 175, 176*. 

Vital Statistics, 119-124 ; 342-344. 

Vitreous humor, 313*. 

Vocal cords, 191, 192. 

Voice, 191, 192*. 

Voice box. See Larynx. 

Voluntary muscles, 257*. 

Warts, 232. 

Wastes, 180*, 181, 183*, 186* 
224-225. 

Water, need of in body, 138; and 
disease germs, 100-109. 

Windpipe. See Trachea. 

Wells, 101-102*, 103*, 105. 

White corpuscles of the blood, 
216*, 217*, 218*; and disease 
germs, 25*. 

Whooping cough, 72. 

Woldert, Dr. Albert, and ma¬ 
laria, 62. 

Worms, 75, 78. 

Wounds, 328, 329*. 

Yellow fever, 65. 

























































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